With the surfeit of spells and other abilities and consumables, the hotbars get way too cluttered way too fast. Yes, you can avoid the clutter somewhat by not having everything automagically added to hotbars on acquisition, but this only really works when there is some other, consistent means of casting spells, using abilities and consumables, and any other such action, that does not rely on having to add a button to the hotbar anyway.
The game should be completely playable without ever using the hotbar. Even when using a controller.
