I think the sweet point is a max of 24 skills, you can bind all of them to different letter key on keyboard, and using just two hotbars. If you need more, the system is more complicated than it can be, imho.

Right now, I just hope there will never be more need than three hotbars (36 buttons total) to get all skills at disposal.

Then, the change job system needs something simple, I actually had to bind each armor set to a slot of an hotbar, using three of them for all the jobs/crafting/gathering jobs we have. It is a waste and the only other option is do it manually passing thru' the caracter window, and that is quite an annoyance when you switch job often.

tl;dr:
more than 24 is too much, imo.