What open beta means for you.

Tanitha: Beta's always wipe before release, nothing new here, its the way things are done, and the way things work well. Anyone who joins a beta should be aware of what they are joining.
The only exception usually to beta's not wiping is usually for pay to play games, where people who have preordered the game can play a short time open beta before release without it being wiped. Its usually done this way to give the pre-ordered players an advantage IE to increase sales of preorders. And also to prevent everyone flooding the new player area's of a mmorpg on release. The staggered release allows players to join the game and move onto higher level areas out of the way.
Many players don't like playing buggy beta's and playing a unfinished project, and playing before a wipe. These players wait for release so they can play a finished polish game with no wipes. The choice is the players, no-ones forcing people to play a beta.
On the other hand, what you learn in beta is invaluable. Players who start on release and then try to learn the game are usually slower and get behind.