The Mac App Store isn't the game changer some people seem to think (or fear) it is. It could very well be a boon to small developers, or it could have no impact at all, but it doesn't change anything.
I don't think it's an enormous change, but it makes it easier for Apple to drop optical drives from all of their laptops. They could do it for the Air previously because it was marketed as a laptop with extra stuff removed - but they could not remove the optical drive in normal Macbooks partly because of this problem.
The other common use case for the optical drive are DVDs and music CDs. Streaming content is making those less necessary.
The Mac App Store isn't the game changer some people seem to think (or fear) it is. It could very well be a boon to small developers, or it could have no impact at all, but it doesn't change anything.