PCars was already 50% off during the earlier Steam Sale in the middle of summer. Also, remember, as a title builds DLC, the base price routinely drops. You may pay $20-$25 for the game itself, but when you pick it up, there may be $40-$50 worth of DLC.
As DLC releases, I'm sure there is some consideration paid to the total price of the game. While $50 is fine for a normal game (and I think PCars has plenty of content in its base form), as DLC stacks up - customers will start looking at the "all in" price.
I told my brother to put it on his wishlist and wait till it hits $25 on Steam to pick it up.
I'm one of the fortunate ones whose game runs fine on my PC with minimal issues (occasional bug, very occasional crash). Race with a handful of other guys, everything is pretty smooth and playable. I'm hugely skeptical about PCars2 and don't think that rally-cross was a good choice (while I enjoy PCars I think they could make it brilliant with a second game if they concentrated on polishing what they've started).
Forza 5 and GT7 will annihilate PCars on console sales eventually, I think this is unavoidable. The mass appeal is far too strong on those titles. I don't think A/C will do that well (severe lack of content despite solid sim stuff). PCars was smart to release before anyone else on the new consoles. They made plenty of money.
I'd have much rather seen them dedicate a good 2-3 years to flushing out PCars1 rather than move on, but it is what it is. I also believe patch 3.0 is the game they probably wanted to release, but after so many delays they simply had to pick a date and release it --- and I do think it was released before it should have been.