So, instead you have to go back to town every 5 minutes to sell crap. Fabulous. I mean, you're gonna sell the stuff either way, but the inventory system just adds on to the trouble. An endless inventory is surely bullshit, but some sort of mechanic to make it more bearable would certainly be more appreciated. Like the DS transmuting system, or adding a few extra inventory "pages", or bags of storage to the game like in NWN.
Then again, maybe we're arguing the wrong thing here, and the problem likes not inventory design but game design in general. After all, when the game gets too fixated on loot collection (like Diablo), there's no perfect way to accommodate that. Although, I've played a few Diablo-clones where loot in itself wasn't quite so abundant and there was no bullshit item improvement system, so the inventory felt just about the right size.
Yeah. I don't see a problem in that.
The problem is that those things are rare (esp. runes), and you need to grind a lot to get them, and usually want to keep them for quite a while. At a certain point, though, you pretty much run out of space to keep them.
As for the FO3 vault: it's bullshit design. Not to mention that it's longer and more useless than FO2's temple, you can't readily skip it in any way. "Leaving the vault" save does little good, because you're forced to play the character with the same exact appearance if you use that.