I've seen several people complaining about the trade UI - specifically that it was copied from DOS (with the barter aspect of it, the scale button, etc..) and that you have to drag item to move them instead of clicking.

But there is a toggle button at the top of the screen to switch between barter mode and "regular" trade mod. and you can just double click an item in trade mode to sell it.
Am I missing something? Or were people just too trigger happy with the complaint?

I dont see what all the complaining is about either. I find it to be a perfectly servicable trade window and didnt have any trouble figuring out how it works.

I had a bit of trouble figuring it out but it's not at all a bad system. People are just being grognards.

I think the issue is that it's unintuitive and there's no explanation as to how it works. It's a servicable UI but it's out of the ordinary for these types of games so I think it's reasonable that people wouldn't pick it up right away.

This. My first trade I accidently gave away my whole inventory as I didn't know I could press the scale. And even though it works, it needs some improvements. Why force ask me if I want to split every time I try to sell a stack? Since nothing is final until I press barter, that decision should be up to the player when to initiate. And not only the trade ui is confussing. A lot is. But I have no doubts that the ui will go trough several different iterations before final release.

XD I feel you. I just stick to the "normal" trade UI.