...I'm not sure what your complaint is. Normally, without trading, you'd be unable to do Shield of Arrav and Heroes, plus whatever quests require those (probably quite a lot). Are you saying there should be no trading at all, and those quests (plus any content associated with them) should be inaccessible? Or that, as you said, the workaround should involve the quest just finishing early once your solo part is completed? Allowing certain quest items to be traded IS the workaround. I suppose you could just not do the quests if this isn't what you want?