CapnZapp
Legend
Sorry, that train has left a long time ago.If the statistical distribution of NPC stats does not conform to the rules presented for PC generation, then it creates a lot of problems. Invariably, it means that PCs don't play by the same rules as anyone else; and when the rules of the game reflect the reality of the game world, that basically amounts to codified meta-gaming (i.e. you succeed at the task because you're a PC; which rather cheapens any victory you might earn, when you know it's only because the rules are biased in your favor).
Even worse, unless the writers go out of their way to write up an entire separate set of rules for NPCs, it means we don't know how the rest of the world actually works. If the statistical distribution of NPC stats does not conform to the rules presented for PCs, then we have no idea what their distribution actually is. If a PC halfling is just as likely to have Strength 20 as a PC half-orc, and those rules don't apply to NPCs, then we can't extrapolate out how strong the average (or top 10%, or bottom 10%) halfling should be.
And to what end? To remove a couple of limitations on possible character concepts? Games are built on limitations! If you don't want limitations, then you might as well write up your level 900 god-king with all of the powers and magic items, and then never actually play them because characters without limitations are boring.
Monsters (including humanoid NPCs) already don't follow the same rules as PCs, so you're bringing up a problem that WotC has already decided is not a priority. Keeping DMs from having to create monsters the same way players create PCs was deemed much more important (and rightly so if you ask me - in fact the way 3E handled NPCs was the specific straw that broke the camel's back for me).
Thus the answer is no, all those problems aren't nearly as insurmountable as you make them out to be. Yes, there's codified meta-gaming, but you'll have to realize most gamers view that as an acceptable price to pay.