I think required food would be a nice feature to have, not so much for the realism but for the added challenge; you wouldn't be able to spend forever in a dungeon or in the wilderness without resupplying or being able to find food.
It would be irrelevant though if you can just stuff a ton of food in your pack and keep it forever. Spoilage would be one way to handle it, but it might be more palatable to most people if they just tweak the encumbrance. It seemed like the encumbrance of weapons was boosted a bit in Oblivion relative to other things, maybe to make you consider your choice or weapons more. They could possibly bring it down closer to everything else and then also make lower maximums. A longsword was like 4x the encumbrance of a pumpkin but I think it might be easier to pack more swords than pumpkins.
I don't think encumbrance should be used for weapons at all inside the "how much weight you can carry" system. I think you should have a number of slots for where you could fit swords, bows, daggers, etc ... and when you have as many as can fit on your body, then that's all.
I think encumbrance (weight) should be given to everything else you carry in your pouches and backpack. So if you're small, you can carry 3 or 4 swords and daggers where you can get to them. But if you're large, you can carry 6-8 such items. Then just make amount of weight you can carry for the rest of your items be lowered. So that swords are more about space ... how much space they can take up on your body. And leave the other things to be about weight. Then if you want to carry a pumpkin, and it weighs 40 pounds, and you can only carry 45 pounds, then pretty much you're carrying a pumpkin and that's it. But you still can wear (and carry) the daggers and swords you're capable of wearing extra. So that they're left seperate. What's the difference? You pretty much always have a place for multiple swords and daggers that you can sell in town when you don't need them, leaving you the space to put more of them later as you discover them.
That way, instead of going into your inventory and equipping different weapons by essentially taking your backpack down and taking the dagger out of it, putting it back, and then using it in combat (which all seems ridiculous) you could just quickly reach over and pick the weapon you want and which is already ready to draw off your body.
If they wanted to use the old system of "put the items anywhere in your inventory" then they should make it extremly slow to switch weapons in combat. Like a switch-weapons timer. You select it and have to wait 10-20 seconds before the weapon switches. But if you wore it on your belt, you could just automatically draw it out and use it. "Quickdraw" ... hahahaha.
Just to clarify one more point: while I said weight shouldn't apply toward inventory, I do think the weight of the weapon should apply toward it's use in combat. Thus, heavier weapons would take a longer time to swing. A light weapon could execute more strikes per minute than a heavy one, but with less impact damage overall than a heavier one, which could break bones, etc... So yes, weight should be there, just (in my opinion) not used for the inventory aspect.
I don't know if I made much sense ... I hope, anyway. Thanks.