I don't play computer games; I've never ordered or pre-ordered one, and I've never had to worry about downloadable content. I don't know what the specific situation is with WHTW.
However, I think I'd be unhappy if I did buy a game for a particular price, and then found I had to buy more stuff to make the game playable, or at least worthwhile playing. That sort of approach might be legal, but it feels like rather poor commercial practice. I'd also be unhappy about paying for a game before it's been released, unless there's a guarantee of getting my money back if it's not up to a reasonable quality.
On the other hand, I can see that pre-ordering is helpful for the manufacturer - it produces a useful stream of income while they're doing most of the spending on game development.