From what I hear in some trans groups, some people find the idea of drag offensive as it paints the idea that all transgendered people are drag queens, and it confuses the public.
I think some feminist second-wave throwbacks often are angry at drag for denigrating the holy sanctity of the female form, or something like that (second-wave fans are fairly demented)
Which is probably the last thing I ever got into a verbal argument over. If gender roles and perceptions are fluid, then the expression of that side of someone through drag (queen/king) is essentially just nothing more than an extension of someones queer expression and should never be considered as anything other than that. It's a truth, not a pastiche.