Probably because most people playing a beta just see it as an opportunity to play the game before it's released. Most people don't understand that they should be _testing_ the game. That's the whole point of a beta test right?
I was in the beta - from the get-go it was clear that EA was interested in using the beta to test their backend, not the game itself. There was no built-in mechanism for feedback or suggestions.
It was a server-stress-test beta (heh, fat good it did), not a gameplay beta.
Also, the beta is time-limited to one hour of play, and almost all buildings were locked out. There was not enough time for anyone to play enough to actually expose these problems (that come about only after your city has grown to some size).
I was in the SimCity Beta1 and tested it thoroughly in the very limited time that was given. It was very hard to test different concepts and parts of the game - none the less, a lot of bugs and a lot of serious issues were found.
I reported 10 separate issues with detailed specifications of my hardware and software setup - with detailed observed behaviour and actions that I could remember were related to the issues.
There was an forum for the SimCity Beta1. There was plenty of individually reported issues discussed and tested by different persons, and there was good creative discussions going on as well.
The forum had the functionality where you could click "I've had this too!" to a main post in the Bugs/Issues sub-forum.
Then again, it was pretty obvious that we weren't supposed to test the game all that thoroughly - because of the limited game time and very restricted game play in general.
It was basically a quick demo play. And that in itself is alright I guess.
EA is large and has a lot of QA/Testers - not sure about the Maxis sub-division though.
