When you read "MMO" in the headline, did you know what it meant? Or did you think it could refer to two different things and you weren't sure which one it was? No, you knew it meant "massively multiplayer online role playing game." That's why it's MMO, not MMORPG or even MMOG.
There are actually three reasons why it is MMO:
- There aren't any other "MMOs", so "MMO" is clear.
- "MMO" is consistent with the MMO-predecessors, MUDs and MOOs (text based, multiplayer but not massively so, and role playing or not).
- "MMO" is also consistent with the TLA standard (three letter acronym) from computer science.
And, truth be told, MMORPGs (I did it for a reason there) aren't very RPG-ish anyways. People don't play roles so much as do what they want. Sure, maybe in WoW or EQII you're a healer or a tank. Healer and tank do fit one definition of "role", but not really in any deep way. "RPG" has mostly come to mean "a fantasy game like Dungeons & Dragons, with elves and mages and such," and really has very little to do with roles as played necessities. Second Life is far more about playing roles (if you want it to be) than any MMO that I am aware of, even though Second Life is not a game, although its sandbox approach allows for people to play games in it (just like a sandbox).
Edit: Apparently this bothers me so much I wrote about it last year, but it's too annoying to keep in mind. Maybe it will become an annual rant.