I didn’t for D2 because I had a feeling that the Beta was going to be the same game and I was right. So my answer is No. I will wait until it comes out and then decide to buy the game.
I wouldn't pre-order, no. I haven't pre-ordered a game since Pokemon Black and White version came out.
But, I wouldn't jump to buy the game like I did with D2, albeit my cousin talked me into buying it.
I would definitely give it a few months for reviews to pour in, before making the decision to buy it or not.
EDIT: and I for sure would make note not to blitz through the campaign in a hurry to get to the endgame that really can't be called endgame, because I'm sure it will be no different with the next Destiny title.
Not just with Bungie, EA, Ubisoft etc.. all release broken games full of micro transactions.. you get your fingers burnt to many times.. I miss the days when you could actually buy a ‘full’ base game, not one that’s been split into DLC’s...