You're so right. I never really looked at it that way but it's true. Would the alpha male as an outsider in certain situations work to make the humor less caustic?
Well, I've taught travel writing and noticed that often the funniest travel narratives are still written by white, straight males because in some cases, the sheer vulnerability of going somewhere like India or Africa or Japan - where you completely stand out and aren't in charge and are not the "norm" both inspires a sense of wonder and fear - and if done right (not in a let's make fun of "the natives" way, but rather a - why is everyone staring at me? way) - and that can be hilarious. Bill Bryson is a master at that.
Paul Theroux, on the other hand, gets away with being caustic because of his own self-hatred and misanthropy. (As a student of mine said, it's like reading "Travels with Dr. House.)
My husband is Hispanic and absolutely can't stand Carlos Mencia. He doesn't think he gets away with it. (Then again, Jaime tends to dislike comics he hasn't seen in anything more than commercials. He complained bitterly about Rosanne for years based solely on the commercials, and then somehow he got hooked on her show.)
I read somewhere that Carlos Mencia's dad is Caucasian - and that he changed his name to Mencia from a white-sounding name so he could "get away" with ethnic humor.
I, too, found Roseanne's humor caustic and unpleasant, but the early seasons of her show were just brilliant. Kudos to the writers who really give those characters life - very few sitcom pull off funny and serious in the way that show did. Joss Whedon's father was a producer and writing for that show was one of his first gigs, good training for the serio-comic tone that made Buffy so great. There was massive amounts of creative tension on that show as well.