This has been on my mind for a while, but since it's likely going to be controversial, I'd rather just leave it up for the community to ponder too, and perhaps we can have a mature and balanced discussion about it.
Right now, we allow all PCs to receive maximum hit points on level up - whereas all NPCs (including all creatures) only get the average. This means PCs often have nearly twice the amount of hit points that an NPC of equal level would have.
The result, beyond the obvious imbalance between PCs and NPCs that this constitute, is that many of the relative balances within the D&D ruleset are warped. Mages become much less vulnerable, constitution as an ability score is made less significant and the same with the toughness feat - not to mention that what causes raw damage (like using weapons) just become much less effective overall compared to magic that has more varied effects.
I wonder if anyone else acknowledge this as being an imbalance though? And in that case, if it's something worth handling, perhaps even some ideas to how?
My own preference is to move PCs closer to NPCs. I don't like the idea of just rolling a dice on level up though, since it makes it way too random, so I'd rather just level it out by some flat modifier. But alternatively, one could also consider simply increasing NPC hit points to match PC progression.
Either way, please don't panic! It's not something that would happen in any near future and not without some significant community support. This isn't in any way meant to suggest that anyone are doing things wrong or otherwise either. I just put my faith in that we as a community are mature enough to be open to the debate, and then we'll see where sensible talk can bring us.