Abstraction has the disadvantage of being... well, abstract.
There are several rules that are commonly ignored in Encumberance. In particular, your clothing/outfit does not count against your encumberance, so wearing a nobles outfit on a weak noble does not put the poor guy into medium encumberance unless he's wearing 30 pounds of jewelry.
I've found the problem with ignoring encumberance is that you end up with players carrying around everything they find, particularly the golfbag of swords ("A Wereshark? Caddy, my #7 Ironsword should be good") or other unreasonable things. (I've seen a player who was carrying so much, that the end weight was heavier than his horse!). On the other hand, meticulous tracking of it can be tedius as well. A good compromise is to have them track most things, on on occasion update it, but don't penalize them for carrying around something extra for just a but (unless that's the point).
But, that is part of the fun of the game, and a balance point as well. Want to be nimble and quick? Either have the strength to lug around all that gear, or learn to do with smaller, lighter gear (or just less gear).
And it's not like there aren't, or won't be carry all magic items.