The quickbar was a great step to streamline the UI but using it still remains fairly cumbersome in my opinion.

In my experience, while you're with your fingers on the WASD alot of cases it's alot easier to just go to your inventory with the tab-key closeby, and right clicking the item you want to use. This is especially true for items like food. Items you like to keep in slots abit further to the right. Using the number keys beyond the third slot require you to lift one of your hands to away from their spot, which doesn't make for a fluid experience so the quickbar rather misses its purpose.

If we would be able to use the scroll-wheel and the MMB to switch between items on the quickbar it would make the whole process alot easier and faster!

I know this would mean a replacement for the "action menu" needs to be thought out, but there's alot of options. An item-sensitive como-rose is one I can think of...