This thread seems like as good a place as any...
Upcoming iTunes 12.4 update to (re)introduce persistent sidebar and other UI tweaks.
Translation: "We've really shit the bed with usability and this new 'flat' aesthetic, so, after two years, we're gonna kinda start putting things back like they were before
Ive and company started mangling the appearance/usability of OS X, iOS and their associated apps. You're welcome."
Maybe they'll attempt something similar for the wretched, impossible-to-grasp Photos?
Maybe this whole iPhone SE situation has caused them to realize how arrogant and out-of-touch they can be, and that maybe *gasp* giving customers what they want/enjoy/understand is a better approach than "here's what we're doing, and you'll like it because, hey...we're Apple. We barely have to try at this point! Where else are you gonna go, nerds?"
Naaah, who am I kidding...it'll be like every iTunes release in recent memory: for every thing it fixes/improves, it'll screw up 2-3 more.