I don't think that drag queens are bad for the transgender communities. On the other hand, I don’t think that they are very beneficial, either. The comedian, Jack Benny, had a drag persona that was part of his comedy acts from 1932 through 1965. If people being aware of drag performers would provide much impetus for progress more generally, then it would have done so during that period. Most people, according to others’ analyses, enjoyed the entertainment, but did not take it very seriously. It was good for a laugh.
On the serious subjects of non-discrimination laws and hate-crime laws, drag queens are mostly irrelevant. Transsexuals are VERY relevant, as they want to go to work in their genders of choice. Part-time crossdressers fall somewhere in between. Most of us don’t want to go to work dressed as women, but we do want some of the extra security non-discrimination laws and hate-crime laws provide. Drag queens do their thing in protected settings; we are more likely to go to a variety of public settings (restaurants, etc.) where discrimination and crime are potential dangers. (We can minimize those dangers, however, by going out in groups rather than as isolated individuals.)
Drag queens are part of our communities, and that is good; but they are not likely to win over the hearts and minds of the general public. We need that; and transsexuals need it even more.