Like the religious right says, "it's all just a choice," so ditch the bitch, flip the switch, and start banging your buddies, straight guys!
Seriously, though, this isn't new or unprecedented - they're asking a different question (the key word is "mostly") and men feel more free to be honest in today's society. There was a time in parts of American society when male homosexuality was perfectly okay as long as one was the top. Read George Chauncey's "Gay New York," for example.