You are fighting the dragons. Why would you want to become the enemy? It may be cool stylistically, but storywise I think it would ruin it...and I wouldn't want to do it anyway.
Also, on a somewhat related matter I would much rather have my character become the emperor in the end.
This....i think we'll become the emperor.
As for i wouldn't want to do it anyway....i would at least try it,for the experience.
And i love dragons,but in all i agree with you.
Also i think that after skyrim ends,i dont think that will be the last we see of the dragons