I agree that Tomorrowland Terrace (and Tortuga Tavern for that matter) should be open regularly for food service. That is a somewhat different issue than where to build attractions though.
Regarding Stitch, I'm totally on board that that space needs to be reopened as a new attraction. It's pathetic having that sitting there unused within the busiest theme park in the world. Even a "lesser" attraction would be of value - think something like the Cars Racing Academy attraction at DHS - by providing another thing that can occupy guests. That space though is pretty small and wouldn't really accommodate a "major" attraction, certainly not something like Tron that despite the naysayers on here will be quite popular among many Disney guests.
But anyway my point going back was simply that MK doesn't really have abandoned space the way some of the other parks do. Underutilized perhaps, but since they actually finally reused the 20K plot, the choices for attractions (outside of Stitch theater) for new attractions at MK would either be construction on new space or replacement of existing attractions. I think most all of us would agree that MK really needs expansion and new capacity over replacing existing stuff. And the park - all WDW parks - have the space, they just need to use it.
It's just sad that they often will figure out out to add more guest areas to DLR and increase the already high attraction count there, but constantly replace things at WDW even though there is crapload of rooms to add more. In some cases (replacing the very large and outdated Backlot Tour) I can understand, but a lot of them (GMR, Energy, Maelstrom, SWSA, etc) it strikes me as pointless just spending money and running in place instead of making substantial improvements for guests.