Honestly, I'm surprised The Simpsons Movie didn't cause a tsunami of movies based on current TV cartoons the way The Rugrats Movie did. There hasn't even been a TV cartoon-based movie since Simpsons! I guess studios don't want to invest the money, but technically Hey Arnold and Powerpuff Girls did make profits - barely, but profits none the less.
I've said it before, but the US is confounded by current TV cartoon based movies. There have been a few of them, but they tend to disappear unless they're huge names. DIC's Heathcliff got one (I don't recall if it was actually released in theaters), but it was a clip show (like the Looney Tunes movies up to that point... makes sense because Mel Blanc was the voice of Heathcliff). Bravestarr had one too, and it was far from a success and it hampered the popularity of the TV series. And then there's Chipmunk Adventure and Batman Mask of the Phantasm. I don't know how well they did, but they got more cult than anything. Not to mention the fact Disney didn't figure out that February vacation sweet spot that worked for Doug, Recess, and Teacher's Pet (actually, that was in January) for Ducktales, which killed any plans for TDA based movies.
For some reason, it's much more financially sound to wait 20 years, hire the wrong cast, hire writers who have a bare understanding of the concept (or just have a script that's a similar concept to attach to a soon to be expired license to crap a movie out while they can), and have it bomb even worse than a current cartoon would. Seriously. You have the Flintstones, the Smurfs, and the Chipmunks.... then everything else. 3 successes, a whole mess of failures.
I wish we'd adopt the Japanese animation festival model. An anthology of short films of varying length based on cartoons that are currently on the air that add up to a feature run time. As it stands, I'm pretty much going to have to see that *&^% Ice Age 4 movie for the second ever theatrical Simpsons cartoon in that show's history.