Memory cards are different anyway. 99% of camera owners buy one memory card for their cameras at the time they purchase their cameras and they promptly forget about it. The differing memory card formats cause hardly any inconvenience to the consumer at all. In spite of that, of course, the market has chosen an unofficial standard with the SD card. There are others out there, of course, but . . .
At any rate, like I say, it's totally different. It would only be an apt comparison if you went to take a picture of your kid at his football game only to have your camera flash a message at you saying that only memory sticks are compatible with football games. But then when you had a camera with a memory stick you were confronted with a message saying that memory sticks are incompatible with birthday parties.
I think there is merit to both sides of the argument. On the one hand we get competition, theoretically bringing prices down, on the other hand we have convenience and simplicity. In the case of a media format for watching movies, I'll take the convenience. I don't think the competition brings much to the table in this market, but keeping track of which format each movie is released on is a pain in the ass, and having to miss a bunch of movies you really want to see (or own two different players) is an even bigger pain in the ass.