Well, i can only see advantages on this, for gamers and for the Obsidian team.
1- The user imput
We all now that one of the major problems with obsidian games are the horrible bugs their games have (its true, sorry mates haha).
Same with some mecanics that are not fully tested because of either lack of time or the tester team wasn't really good (i heard somewhere that it wasn't obsidian who did the testing for KOTOR, not sure if true).
If all the backers have access to the beta i believe the game we bough could be so much better...
2- Much more early access to the game = more