The way I see it, if they did a full wipe they would have to refund all the Zen purchased for this game. Huge exercise, but they should have the records to do it. The problem is, if I understand correctly, they would be giving up two weeks (that is how long the Beta has been running for? I forget) of revenue. They must have made loads from this game already and I don't think they would want to do this.
If they do a full wipe then they risk people leaving as effort would be lost, even if Zen was returned. However if they do not do a full wipe then they may loose customers. So damned if they do and damned if they don't.
I personally think that with either option people would return after they get over it. I would personally prefer full wipe as, while it would be annoying, I would get over it; we have only been playing for two weeks after all and it is an MMO. I would certainly not mind leveling again two much tbh. However I only got to level 30, I can imagine if someone had got a toon or two to 60, and sunk in some real cash and time for the trouble, would feel differently.