It depends on what you want grades to express.

If you want grades to express students' strength relative to each other, a quota of say 35% A's per course might be appropriate.

On the other hand, if grades are meant to show how students do an a more objective and time-invariant set of criteria, maybe grade inflation is OK. Maybe it means that student's are getting generally smarter, or more efficient at learning. IQ has been rising over time as well, as has efficiency in many workplaces. Perhaps grade inflation, at least partially, reflects this as well?

I am not saying that this is the case. Rather I would like to throw a hypothesis out there, as it is one that is not often expressed. I would love to hear arguments for and against the above ideas.