You do have a point there...but I'd also like it if, like the OP states, there were penalties for not doing so such as:

not sleeping = fatigue recharges much slower, magicka and health don't recharge
not eating drinking= fatigue recharges much, much slower, health actually goes down but slowly

drinking alcoholic beverages = blurred vision (type and amount of drink dependent), stumbling - they do this in other games already - Stalker and Boiling Point are 2 that I own that have this implemented.

being wounded = causes stumbling, limping, drains fatigue & health slowly to simulate bleeding

I know, none of this will ever happen unless a mod does it, but it's fun to dream.