I totaly agree with red.
and to add to the point, Ya see, the thing is that FH is very much nature based, you don't get many man made looking maps. So to put these maps into the game could probably throw off the theme a bit, and as far as I know, Kovu wanted the game to be as realistic as possible (Hence his reluctance to put the wings in).
I mean, if you had mentioned maybe putting reds map pack in, instead of feral city and feral cinema, then I might agree with you more there, but even then, I dunno if it has meshes taken from other users? I didn't really see any, but you can never be sure.
So, as awesome as the idea is, this along with what Red said, is the main problem, but it was an awesome idea floof ;3