JRemote
A few years ago, user LesPaul developed JRemote and it proved to be very popular. I asked him if he might like to sell it to us and work for the company full time. He eventually accepted. After about a year, he quit. This left us with code written in a language we don't normally use, on a development platform we don't use, and no significant expertise on iOS. So JRemote continues to be popular, but we don't expect to work on it.
Well, these kind of things happen if your bus factor is only one. However, that was long ago. In the time that went by since then, you should have found a solution. Let a team member learn these technologies, make Gizmo more like JRemote, develop a new alternative, hire someone to further develop JRemote or port it to a language you want. However, not doing anything is just not a good idea.
JRemote is not a finished product. It misses important things like being able to select different audio/subtitle streams. It's cover art caching strategy is absolutely horrible. Playing a searched item still not works and plays the wrong file.
Tidal, Spotify, etc
We have done many implementations of such services over the years. They all went out of business. We won't do more unless we see a proven business model (in other words, we can earn money by doing it).
The streaming business is like a boat. It's a place to pour money. They don't make a profit. Sometimes an owner gets lucky and someone else buys the business, but usually they expire.
I've kept a log of failed (and failing) services here:
Why Streaming Struggles
The big important streaming services did not go out of business. Itunes, Spotify, Netflix, Amazon Prime Video, etc. are here to stay. I understand that you don't want to implement all these services because they need a lot of maintenance and there also some jurisdictional problems because some providers don't allow selling products that access their APIs.
However, not doing anything is not a solution. The answer on how to tackle this problem is the same as 5 years ago: Plugins/Addons. The important services will always have some volunteers in the community that will maintain them. Setting up the API will be a lot of work, however it will provide so much additional value. Imagining to have all Netflix series and all Spotify music in my MC is just wonderful.
A Simpler Interface
While we could change the interface, and move somethings around, I don't think it's possible to make an interface that is both simple and powerful. Moving things would also be a problem to people who know the interface well. Windows has changed their user interface for networking so many times that I've given up trying to understand it.
A More Beautiful Interface
While I've seen this requested many times, I've never seen a design and I doubt that people could agree on what it should look like.
A More Intuitive Interface
Same answer.
But we are always open to suggestions. And we have built a few interfaces that use MC's engine.
Theater View
JRemote
Gizmo
Panel
These are all very different and are all heavily used.
As LesPaul proved, you can use MC's MCWS interface to build something very complex and good looking.
My experience with MCs interface is that the JRiver team very very very conservative about it. What were the big changes to the interface in the last 5 years? Well, there is a new tag window, which is cool, but other than that?
Like you said there is not one perfect interface. But you should provide a good default interface and the building blocks to make it better. But fact is, you don't supply the blocks needed to do so. One thing that is needed is the ability to use cover arts for arbitrary tags and actually this has already been implemented. But someone in your team decided that cover arts are only allowed for series, albums, artists. If I want to use a cover art for a genre, then I will hit a wall. Another thing that is also needed is the usage of widgets. If I want to display stars for a rating or checkmarks for completion I can use them. But only if I am satisfied with text stars and text checkmarks. If I want to be able to click on these stars to change the rating, then I hit a wall again. The customization of MCs GUI is not really where I would want it to be.
There are also some other things wrong with the interface besides customization.
One is that the scaling of the cover art look blurry because it uses a thumbnail instead of the real thing. I've complained about this multiple times in the last years, without success. It is quite obvious to me, that there is no one in the JRiver team, that understands the importance of eyecandy. A new user will always first look at screenshots and those should be as clear as possible. This is a big issue that should have priority. The interface should always have priority over new features.
Another problem of the interface is how the spacing between covers scales with the window size. The spacing should not scale at all and should always stay in the aspect ration 1:1 or coverwidth:coverheight. Currently the spacing changes every time I re-size the window and I have to re-size it or live with an ugly spacing.
Will JRiver Earn More Money?
That's the cruel question that every business must ask. I have an old accountant friend who likes to say that the key to success is that income exceeds expenses.
We have a first rate, even world class, development team (more or less in order of their time at JRiver):
Bob, Yaobing, JohnT, Matt, Hendrik, and Brad. Keenan works in the summers. I'm part of the team for some purposes.
These skilled craftsmen do an amazing job. I'm extremely proud to work with them. But we have limits. To work well, we need to respect these limits. We can't take on every project.
Of course, money is important. But I think you have a pretty bad intuition on how to generate money. If I look on things you have implemented in the last years or wanted to implement, than the verdict does not look good for you. A good example is the Kickstarter campaign you started. The result showed you, that there is absolutely no interest in an area where you have expected it. There is also Engen, which I predict will be unsuccessful because it is outside your core competencies and it only supports Z-Wave. There is literally a graveyard of "features" you implemented and which are unsuccessful.
You have also put lots of work into the TV part of MC, which is not really the place where I would put it. The trend of cable subscriptions is declining. People are using streaming services like Netflix and co.
On the other hand other areas like series and movies skyrocket in the mean time. In 2011 there were about 435k XBMC users. Now there are 38 million Kodi users. That is 87x as much as before. There is your money. These are the users you need. So the question is why are the using Kodi and not MC? Better customizeability through plugins as well as more powerful skinning. Raspberry Pi support years ago.
What you need to do:
Hire a designer: Someone that can update your website, all the old skins in MC, the forum, etc.
Get the old stuff out of MC (the old Skins that look like they are from 2000, 3d view, etc)
Fix the issues with the interface (scaling and spacing)
Allow more customizeability of the interface (cover arts for arbitrary tags, widgets in the thumbnail text)
Allow more customizeability of the views (subtags which can be used for different depth in views)
Implement the ability to write plugins for scraping/new types of views(including theater view)/streaming services.
Get one of the developers to learn the technologies used in JRemote.
Speak with your community before implementing bigger features.
If your budget is not sufficient, increase the price (Plex and Emby are significantly more expensive). A more expensive product is better than a stagnating product.