Lack of excellent table service dining options. Brown Derby is great, and its outdoor lounge is a tradition at this point. But that is not enough for a theme park when you compare it to the others Disney has in Florida.
Epcot is a paradise for choices of restaurants. So instead, let's compare it to AK and MK.
AK has 3 consistently positivley reviewed Table Service Restaurants: Tiffins, Yak and Yeti(so good), and Tusker House. MK has Skipper Canteen, The Plaza, Castle, Tony's and Be our Guest. Not all of those are good, but the monorail and boats extend MK to have multiple other TS restraunts at resorts with some truly great signature dining as well. So MK feels like it has more by extension. Easy access to Trail's End alone makes MK better.
Look, there is nothing ludicrously wrong with Mama Melrose's(other than location, its so hidden). It is fine. But it pales in comparison to every other Italian place around it. Whether that be at the Swan & Dolphin, Boardwalk, or Epcot.
50's Prime Time has been bad for a while(subjective).
Hollywood and Slime
Sci-Fi is awesome themeing with decent food(its pretty pedestrian tbh), but its just better burgers and fries for more money and time. Its not unique food wise. But its fun. Needs a more fun and unique menu using the same style of food. However, little kids are crying in there due to the "fear" of the movies a lot(at least for me). So theming wise im not sure little kids all love it, this is subjective of course.
50's Prime Time and Hollywood and Slime need redo's. Sci-Fi could use a more creative menu, nothing weird but more unique burgers and Appetizers could help.