Roon's supposed inability to allowing you to browse by folder used to really annoy me also, as that's how I was accustomed to choosing what I wanted to listen to. However, my folder structure is by Artist/Album/Track. So browsing Roon's Artist view is really identical: choose the artist, choose the album or dive into the tracks. What different about that? Well, speed for one thing. In a raw directory listing you can more quickly scroll to the "S" section to find Supertramp more quickly than paging down in Roon. But I can just type "super" and Roon presents me with a list in seconds that includes Supertramp. So is the raw listing really quicker?
Granted, when you're just noodling around its faster, but if you're just poking around is speed an issue? Or searching for that band you can't remember (starts with a P I'm sure...) maybe it is quicker to scroll a directory. But surely I remember more than just "P" - maybe a band member, a track, genre etc that will help me do a proper search instead of scrolling until something catches my eye.
Anyway, I'm getting used to Roon and liking it more all the time. I totally get the desire for directory scrolling and it annoys me that Roon just dig in their heels and say No, look elsewhere if that's what you want. But I'm more and more OK without it. YMMV obviously.
Cheers,
Robert