There is a lot of discussion here about what kind of interface the game should have, at least with respect to the hotbar. Here's my $.02:

1) I want expandable hot bars. I have a large monitor and want to take advantage of that real estate. That's kind of why I got multiple large monitors in the first place. Please let me expand the bars horizontally and vertically.
2) I want an option to self-sort the hot bar so that the spells, scrolls, potions, etc., are all grouped with each other. Perhaps whether it is sorted or not can be an option.
3) I want the option to turn off automatic additions to the hot bars, so that I can decide exactly what I add. I know that sounds like it conflicts with #2, but I'm fickle.
4) I'm old. My eyes are not what they used to be. Finding those tiny buttons on the hot bar to scroll up and down or switch states isn't as easy as it used to be.

The user interface is second only to content in importance in a game, at least to me. A bad interface can make a less enjoyable, awkward, or completely unplayable. It is worth spending the time and resources to get it right.