My take, for what it's worth:
Studios was originally a quick reaction to Universal opening up down the road. A reaction is rarely as inspired and thought out as an original idea, and it indeed was slapped together more quickly and less deliberately than Disneyland, MK, or Epcot. When it opened, it had Great Movie Ride, the Back Lot tour (with Catastrophe Canyon), and almost nothing else.
It was also supposed to be a working studio, where guests could appear in skit-like productions or even as extras in movies and shows. As far as I know the only things produced there were Golden Girls, From the Earth to the Moon, and Disney promotional videos. In short, nice idea, but not good enough to be sustainable because Hollywood types don't want to be away from Hollywood. It all closed years ago. And with it, all the production space, warehouses, and sets (like Streets of America) became unused, for the most part.
Along the way came the thrillier rides: Star Tours, ToT, R&R, and shows like Indy, Beauty and the Beast, Little Mermaid, Muppets, LMA and Fantasmic. Special stuff, like Star Wars and Soap Opera Weekends and Osborne, brought in people. But it was still a hodgepodge, which was part of its charm. Yet it always lacked an overall identity compared to the other parks.
Now, they're taking wasted and/or under-used space and are turning it into something much better and more focused. Hooray! Keeping the underused stuff, like the very expensive to run LMA, makes no commercial sense. It's day is done. Similarly, SOA is underused walk-through space that's kind of a downer when it's not filled with Christmas lights, and that land within an existing park footprint is very valuable. Put something better there. And, put something cool like Star Wars within walking distance of the entrance instead of a mile away. After all, that extra distance kills things, which is probably one reason why LMA wasn't as popular.
I've been going to Disney since 2003, and I only did the Back Lot tour once, and LMA thrice. The only time I moderately enjoyed SOA was when the Osborne lights were there. No business person would keep this stuff when something so much better can replace them. Plus, that underused stuff is both expensive to run and/or gets in the way of something great. Why dilute the park with mediocre?