Why are baseball stadiums different from one another? History has a lot to do with rink size (Boston garden vs. Montreal forum) etc.
Hockey basically started in Canada and adapted to Europe. Since the IOC is a European club, the Europe game is what became Olympic hockey.
There are pros and cons to changing rink size but I would go with tradition, specially considering that a rink size is essentially a fixed parameter that can't be changed after the fact. I watched a game on Olympic ice this morning and I don't agree that it speeds up the game. In many ways it slows it down (even though there is more skating going on).
2 related historical notes
Scandinavia and Russia play an outdoor hockey game played on frozen football fields. Needless to say there is a lot of skating and no checking. I am not even sure of they use boards.
The formal game of hockey was started in Canada, that much is known. However, the development of skating as well as the first games of field hockey on ice may have been played in Holland on frozen canals (you won't hear that at the Hockey Hall of Fame). The main museum in Amsterdam has a troubling painting that shows just such games many decades before the hockey game was formalized in MTL in the late 1900s.
Full blooded Canadian