I bought the pre-sale pack, but I admit I'm a sucker and play this game way too much. These team ups definitely seem like more of a new revenue stream for them than a big boost for our characters. I don't think they are worthless by any means, even if you just use them for the passives, it's a nice little bonus.
Either way, I don't mind tossing them some cash to help fund future free content, ie raids, new zones, etc.