I can only speak for myself, but I wasn’t intimidated into being a softie as Scoble puts it (I certainly was the first time I met Bill, but not yesterday). I asked a question that I thought was both interesting and had a high likelihood of actually being answered. You can be a tough guy all day long, but asking Bill “With it’s worldwide dominance why does it take so long to get a new Operating System out of Redmond?” isn’t going to lead to an interesting answer.
I interview companies every day, and there is only so far you can go with the tough stuff. People just shut down or go into PR speak when you go to far.
I’m not concerned about not getting invited back by asking a tough question, I’m concerned that I won’t get an interesting answer.