Lol, I just saw this in a commercial for the movie last night!
I am a
huge REO Speedwagon fan. They are my favorite band. And on one hand, I'm not sure how I feel about the song being in the movie (even though, based on the commercial, the characters really seemed to be getting into it and singing their hearts out with it, hehe). But on the other hand, I think it's a very cute and an adorable way to introduce REO Speedwagon (or at least their songs) to younger generations. "Can't Fight This Feeling" is one of my all-time favorite songs of REO's, and who knows... maybe someday in the future, a young kid now hearing the song in "Horton..." will hear the original version and become an REO fan. That's a common way for fandom to begin nowadays.
REO Speedwagon songs have been everywhere recently... in this movie, in multiple commercials, etc. And it's very interesting to see. People's opinions about things like these are always so different... it's either a compliment to the band or an insult to the band, etc, depending on how it's done. But I think it can be a very good thing! And in this case, I thought it was pretty adorable!