when i read about there being a classic demo i initially though they would let you level to 20, because that's what is on offer for trial accounts.
hearing that you start at level 15 though is disappointing. mostly because a lot of people might be interested in doing the level 10 class quests. hearing that there may be a time limit in place (they did say may in the dev watercooler post) is a bit disappointing, but makes sense. they do not know how popular the demo will be, so have to manage expectations and look at server capacity so crashes do not happen.
all in all, i'm more disappointed that characters start at 15 more than anything else.