There are downsides of being limited to 5 action bars sure, but there's a silver lining in the cloud: It's also going to be much easier in theory, for the game developers to balance things this way.

So perhaps, something like prestige classes can be added, that make certain class specific abilities unavailable while they are on the action bar? Here are some ideas, although the names are gonna be disappointing and uncreative as they are mere examples- if any of these abilities are put on the action bar, magic using abilities become unavailable to balance them, and weapon switching won't work to exploit that either.

Here are some ideas to make people who wanna play a pure warrior who hates magic more viable. All of these abilities would be put on the hotbar, and make magical spells unable to be used, until they are taken off the action bar, and maybe add a several hour cooldown so it isn't abused.

Berserker: This is a warrior who isn't the best at one on one combat, and isn't the best companion for a healer, and who is squishy... But whom can do MASSIVE amounts of damage. Having the ability to kill anyone that doesn't sacrifice massive damage to be a tank in just a few hits- easily so long as they get within proper range, and a spammable charge ability. The berserker would be balanced based off of being squishy, and having no ranged weapons and no magic, and being worse at 1v1 as well as worse at teaming up with a healer than the other two.

Duelist: This is a pure physical warrior, but specializes in one on one combat, contrasting with the Guardian.

Guardian: Imitation of the typical warrior class in so many rpgs, you know, much much weaker without a healer but much more powerful with one. This class would receive buffs to damage output, speed and everything when being healed by another player, and a long lasting but temporary max hp buff upon being healed. This revolves entirely around that whole, devoted team player that constantly wants to rely on teamwork with healers.

Juggernaut: The Juggernaut would be the archetypical tank, and would have aggro holding abilities for PvE, and several stuns/peeling abilities to protect allies in PvP, the Juggernaut would also by far have higher hit points than anyone else.

I don't intend on going pure warrior, but these were some ideas I had for people who wanted that, attempting to make multiple playstyles for very different types of non magic using characters.

Pfft. No need to get so complicated about it. Warriors are easy to please. Whenever they start complaining, just give them a bigger axe or sword or whatever. Warriors are happy because they look meaner and mages are happy because warriors are even easier to hit with lightning.

or people that want to be pure warriors could use self control and not use magic or magic items.

Although given how the game is set up, that'd mean insta-death in most situations...