I may be misreading things as well, so it will be interesting to see others comments on this.
As for why drivers need to block suspend, if you set the system to be hyper eager to suspend, then you can't count on getting anything finished unless you block suspend.
if for example, your driver needs to send a string of bytes to your GPS chip to initialize it, having the system sleep in the middle can leave you with a uninitialized device that won't work when you wake up and pick up where you left off, so you need to block suspend while you do this 'critical, uninterruptible' work
the problem that I see is that I haven't seen anything that would prevent an application from claiming that everything that it's doing is critical. It's definitely easier for joe random game developer to just tell the system to not suspend while the game is running than it is to properly handle being suspended.
sometimes an app blocking suspend is the right thing to do (think a 'flashlight' app that just displays an all-white screen and prevents the system from sleeping until you do something to turn it off), but without any way for the system to prevent abuse, it's only going to be a short time before apps start abusing it.