I really don't like being forced into the tree either. for me, the view header always felt 'closer' than the tree, more intuitive, and more productive, allowing more flexibility and choice.
Having said that though, this is MC13, not MC12...
MC9.1, (or was it MC10?) had a 'location bar' which was super useful and sorely missed when it got dropped but the world did not stop and we're still here today, with workflows adapted to take up the slack left by the absent location bar.....
Now we're relying on the TREE? Sorry but that feels like BACKWARDS to me.
Try not to look at it as 'backwards'. Look at it as simply 'different'. Coming from MC12, with it's all-powerful view header menu, can be a tad jarring, but if you take some time to play with the MC13 way, you should be able to find a reasonably comfortable setup. You'll certainly have a busier tree than you had before
If the tree is closed, I have to squint to find the tab to open it, select Music view scheme once, then once more because they no longer auto-expand, and then choose a view scheme that is set to Albums as opposed to genre tiles.
If the tree is closed, you should still get the pseudo-tree drop-down from the view header. This is an indespensible feature when browsing with the tree closed.
I know I'm missing something so I'll reset and explore. It's always like this with something new, but my spider-sense is tingling.
Make a library backup, or make a new library. This will allow you to explore the default tree setup, mess about with a few things for yourself, then revert back to your probably personally tailored tree, hopefully better prepared to introduce it to the MC13 way.
I don't think you're missing anything btw, I think you've more or less got the concept. It's not
so bad once you get into it. Tabs will be your friends!!
-marko