Now you are throwing apples and pears and bananas all in one basket, very great argument.
Honestly, social skills are so poorly implemented, you could really argue, why there are even there.
One guy has to have bartering and probably persuasion aswell, because they are the only social skills with synergy. But often the guy with persuasion won't even be the guy, who will be the one with the persuasion challenge, because the NPC adressed somebody else and the persuader can't join in. So either it is wasted or you have to reload.
Thievery and Lucky Charme would be synergetic aswell, but you don't get that many points to up both fast enough, so you will have to split both on two guys. Mean one guy will have to lockpick the chest and a second guy needs to loot the chest, before he can than sent the stuff most likely to the third guy the trader, or perhaps he first has to send it to fourth guy with loremaster, who can identify it. So for a single player it is a lot of tiresome micromanagement and for coop it does hardly enrich either. Because one guy will all do the trading and talking while the others can't do much during that time, because cooperative talking is hardly a thing anymore. Same goes for the time while the looter is looting. Which also means only the looter will have the real feeling for exploring and treasure finding.
Regarding Loremaster, it is also an annoyance, that you can only loremaster if it is the turn of the loremaster character, even if the loremaster character is one of yours. So you kind of force the loremaster guy to be the one with the highest initiative.
Coming back to the trader: Having to send hundreds of items to the trader so he can trade them is even more tedious than reparing items was. Sure, if you are playing competatively, it is not want you want. But if you play cooperatively or alone, you really would like to be able to either have option shared inventory for trading or to be able to change between characters during trading, so they can add their stuff for the sale directly. Shared inventory seem to work for crafting anyway...
Regarding attributes: autoleveling would be probably as meaningful as everything else, as bland as the attributes are at current state.
