I agree with this sentiment. Dorian Yates said the same thing a long time ago - he said that while 5'7", 210 lb guys can win other contests, the Mr Olympia winner is / should always be a big guy. When you tell the general population that a guy is Mr Olympia, meaning the best bodybuilder in the world, they'd expect to see a big, big guy - read 5'10" and above, 260 lb plus.
Dexter is obviously a great bodybuilder even though I personally don't like his physique at all and he only won last year cause the big guys of quality were out of shape or absent. I have no problem with the best man winning and nor do most people, but that being said, most of us would still like to see a huge, freaky behemoth win. And in bodybuilding, Dexter is big but not huge and dominant in the way Arnold, Sergio, Lee Haney, Dorian, Ronnie and Jay were during their reign.
Then tell the "huge freaky behemoths" to come in shape, when they competed. Jay Cutler didn't (at least not in prejudging) and it cost him his title. Then again, some people complain no matter who's Mr. Olympia, simply because it isn't their favorite bodybuilder. Last time I checked, 5'7", 235 lbs was hardly small. Arnold weighed about the same, in his prime, standing 6'2". Haney was in his best shape as just 5-10 lbs. bigger at 5'11".
The general public will think D. Jackson is a monster and would have little problem thinking that he's Mr. Olympia. Heck, they had little problem thinking Frank Zane was Mr. Olympia, when Zane was endorsing the "Torso Trak", though the infomercials played up his Mr. Universe wins FAR MORE than his Olympia wins.
In fact, the general public STILL THINKS that the Mr. Universe title is the biggest bodybuilding title to have.