"You may find him obnoxious - which he may be, and his movies bland - which some are, but Tom Cruise is in very select company when it comes to the amount of stunt work he does."

If the movies are bland, then who cares if he does his own stunts in them? I don't think there's any need to ask, "Why doesn't Tom Cruise get more props for doing his own stunts?" when Knight & Day is tanking. If Cruise's recent films blew up and made an impact on the culture, then he'd get props, like Keanu did for learning Kung-Fu for The Matrix. (And no, I don't remember the shot you're talking about from MI:1.)

NOBODY is saying, "Oh man, you should go see the stunts that Tom Cruise does in Knight and Day." I don't think anyone has ever said that about Cruise and that's why most people don't give him props. Yes, it might make filmmaking easier (and I think most industry people give him credit for doing his own shit) but the general public doesn't give a rat's ass about that.