The debate is about the price of the game. In my opinion it doesnt matter where the development money comes from. If from a publisher or from a funding project, the money flows either way into the development of the game. Isnt the difference that instead of the publisher getting most of the money from the sales and giving a new project to the developer, obsidian gets now the big chunk to fund their own next project?
So the only question which remains is, if this game is worth the price. And tbh, it BG2 was a game with an equal price X years ago, the price is fine. I mean, obsidian wont buy a jet and fly to the hawaii with the money earned but will fund the next project (i hope at least).
Why was the game cheaper for the backers? Well i see it as a reward for taking the risk. No one could have known how the project will turn out in the end and i could have just said "I let the other gamers take the risk and wait how the game looks in the end", well, thats okay but you then pay the full price.
The lowest backer tier for getting the game is NOT the price of the actual game. Its a probably 60+ hour rpg so the price should be set accordingly. And the price is fine.