In my interview, they asked me if there was anything I didn't get to say about myself that I thought was relevant. I used that time to work in my theatre experience and work in my request (Jungle Cruise or The Great Movie Ride). I still have NO idea if that helped at all, but I was overjoyed to find out that I had been placed in my dream location when I arrived!
IMO, there's nothing wrong with asking. I know someone who was placed in Adventureland for their extension, but at a different attraction. He asked to be moved and was able to switch to Jungle Cruise. There's definitely no guarantee of that being allowed, and most likely if you request something they'll just ignore your email. But that doesn't mean that you'll be fired for asking.
Also- I agree with what people say that the attraction you get isn't the thing, it's all about your attitude/who you work with. I mean, I got lucky and adored my attraction itself. But two of my roommates were placed at attractions they were initially not thrilled at all with- but they have both chosen to extend and stay there because they ended up loving it!
If I can ask, where are you hoping to be placed?