I'll try to address a few of your points. Maybe that will help you.
1. Superior sound quality across the board. ASIO, DLNA/CCA and a desktop Topping DAC/Amp that I am eyeing
First, MC doesn't support Chromecast Audio. BubbleUPNP does. MC supports DLNA.
If you will "always use JRiver to stream to a renderer" as you said, MC will have zero impact on your sound quality, unless you are converting or otherwise processing the audio on the fly. Now you're throwing in a Topping DAC, so if you connect that directly to the PC running MC, then sound quality might come into play.
2. Library management. I set it up once and then it is on autopilot. I don't have the need to tinker with it everyday
I don't know what you mean by autopilot. MC can be setup to automatically import new music that you rip or otherwise deposit on the filesystem. Maybe that's what you mean. But MC is tinkerer's software. Most people tinker. Does it break if you leave it alone? No. But personally I find it unlikely that all your music will be perfectly tagged when you first download it or rip it. Tinkering with metadata is almost always a necessity if you want good metadata in your library.
3. A remote to control the media server from my phone
JRemote is a quite good remote control app.
4. An UI/UX that is expected from commercial software aimed at sensory consumption
This could mean anything. I demur at discussing your UX expectations or ideas on whatever "sensory consumption" might be.
5. Deal with images/videos -> stream from NAS to projector via Chromecast/Roku. Get off Plex!
No Chromecast, as I said before. For video, Plex streaming works better than MC streaming, in my opinion. MC can use a NAS as storage. If you want to "stream from NAS" without a PC, you will need a DLNA server running on your NAS. Getting MC to run directly on a NAS box is technically complicated.
I don't know if this helps you. My suspicion is that MC is more complicated and "tinkery" than you would prefer. There is no easy "getting started guide" nor will there be.
You repeatedly mention streaming, and that you want to stream music to your renderer, and that for video/images you want to stream to a Chromecast or Roku. MC will not improve your video quality in any way whatsoever if you stream your video via a Chromecast or Roku device. If you want MC's superior video quality out of your projector, MC must be directly connected via the graphics card in the PC: no streaming. You are not describing any use cases which take best advantage of MC's abilities.
For someone with "very simple needs", for a DLNA only setup, for streaming only without tinkering, perhaps you should just stick with Plex. You will have to decide for yourself if you like MC or if it is too complicated for you.
To get you better acquainted with interface and the concept of views, I recommend you look at these links:
https://wiki.jriver.com/index.php/Standard_Viewhttps://wiki.jriver.com/index.php/View_SchemesTo learn a bit about customization of views, look at Marko's excellent tutorial:
https://yabb.jriver.com/interact/index.php?topic=68960.0Lastly, there are a view videos that have been created a while back:
https://yabb.jriver.com/interact/index.php/topic,111775.0.htmlGood luck to you...