It's already free for many users...
I think that statement sums it all up. If you want the game, buy the game. If you want to play with it while they work out the bugs and add more things to it, pre-purchase it before release.
Why should they sell it for less or give things away for people to have the privilege of playing a game before the release? Now if they wanted to make people feel 'special' for buying ahead of time, sure give them access to special avatars for the forum or maybe a special DLC item... but those usually get out into the mainstream eventually anyway.
Quite frankly, I have the original Elemental. I'll likely get the fallen enchantress as well as it IS a good game. Just haven't decided to get the per-purchase yet.
Besides, SINS rebellion takes up a chunk of Elemental's time! 
