+1 for lucky charm to be party wide - a loot character sucks anytime. Better yet, remove lucky charm and implement a static lucky to all chests for all characters
I play co-op and SP and I like that the other skills are separate. However,
+1 to the suggestion of having the bartering character being able to access companions bags - in MP, it's easy enough to say, gimme your crap Im selling crap right now.
+1 for having 'examined' enemies stats viewable for the whole party - but still require the loremaster to examine them.
+1 to allowing multiple characters to participate in dialogues (this was in D:OS wasn't it?) My biggest gripe with the way it is now is how many innocent animals were slaughtered when my partner who REALLY LOVES PET PAL was just one step behind me when I stumbled into a dialogue I had no clue was coming.