Sure isn’t an important choice whether to take an ultimate or not, if it is a free slot.
That isn’t how it works in D2 though. Try swapping out necro summons, or a skill on cooldown (definitely not saying that should change would be quite awful).
I actually agree that there are not enough slots. If the game is going to give us items that give us +1 to all X type of skills, then there should be a possibility to use them even if you don’t specialise into them. Otherwise let’s just remove this property altogether!
Diablo 2 had 8 to start with, using key bindings from F1 TO F8 But, you would have as many as 16 skills. id max myself at 10, all my summons as a druid, my town portal, and cyclone armor, and my two big moves at level 30 on the elemental.
This was one of the bigger reasons why I just couldn’t get into Diablo 3, its like a nice game, but I want to be able to have the option to use my weapon as an attack, not have it bind to a skill, at least its more useful in diablo 4. but I play a summoner druid, if I want to use my sprit, either I lose, a summon, or i lose my ultimate, because I need to use spirit to use my one move but i can’t if i don’t have my main attack