Sales are no more an issue now than they've ever been, and if I'm not mistaken unless the publisher officially drops the price the only ones hurt by these sales are the retailers (and if it drives traffic to the store having the sale that's even debateable). The developers see the same amount of money whether Kmart sells No More Heroes 2 new for $50 or on sale for $30.
On the other hand, gamers who wait until "the time is right" is why I'm stuck with Valkyria Chronicles 2 on the PSP. That happened because, while the game did well over time (especially when the price dropped to around $30-$40), it didn't do well quickly enough to justify making the sequel a PS3 project. So yeah, it can definitely hurt when people don't support a game they want to do well when it's new. But what can you do? Games are too expensive, but they're also really expensive to make no matter the console developed on. Unfortunately, it's led to the rise of the handheld market as the alternative.