I like having spells individually on the hotbar rather than having a general spells button with extra clicking or scrolling.
The hotbar is exactly the tool that will make you scroll and search constantly. It already does at low levels. Have you played D&D? High level Wizards and Clerics have a huge ever changing spell selection which will be a nightmare to manage on a hotbar because the spells alone will spread onto multiple pages. The usefulness of the BG3 hotbar ends when you have to start changing pages. NWN hotbar works because you can flip pages quickly with SHIFT-ALT-CTR and I'd like to see similar functionality here.
That said, I wouldn't advocate removing the hotbar completely. It can be very useful for weapon configurations, potions and spells and abilities you use very often like cantrip attacks. There needs to be some amount of UI customization.
