There are a few Feature Requests out there already with ideas to improve the classical experience and it’s hard to tell which ones will get addressed the one way or the other. So discussion on this may not get too much traction. Still it’s important to point out that there’s still room left for improvement. 
With box sets - especially those with a lot of discs - my biggest problem is often not so much the metadata but the out-of-the-box 
browsing experience. If a boxset consists of previously released albums - not a new compilation or a dedicated multi-disc publication - I usually try to split the set into the original albums and only use a tag in Roon to mark the original boxset. Works much better – even though it now forced Leslie Howard (his 61 albums which make the Complete Liszt Piano set) to grin at me three times in the genre browser which can be kind of unsettling 
. If Roon would provide this “split boxset” functionality because it already knows from metadata what the original albums were that would be cool.
If the back cover is a picture in the album folder you can view it inline already. What’s missing is image extraction of file embedded cover art.
Like asked for here:
An interesting feature idea for classical music I remember’s this one: