Because they want to live there. You answered your own question.How come everybody keeps picking the forest temple? Its fine that you want to live there but why does everybody keep picking it?
I'd choose the Water Temple. That's assuming I had the ability to breathe underwater/jump really high, cause otherwise I would never be able to move about. The Spirit Temple was pretty cool but I hate sand. I actually think I have a phobia against it or something, it just gets.... everywhere. Brrrrrrr.