Multiple action bars being visible at the same time would make the game less clunky. Really hope this happens or a mod comes out for it. Switching action bars is very frustrating. Could be quite nice to have different action bars with spell schools, items, or scrolls grouped up.
Items being instantly added to the action bar is another issue. Spells such as flying and bull horns, which add another ability each time feel horrible because of it. Once they run out the charge or flight ability disappears from the bars and those spots are filled up by new combat items.
Keybinding bug?
I've changed some of my action bar keybindings that also happen to be the scroll up and down on action bars, but every time I load the game again they're reset.