I believe there are plans to allow you to make bland, personality-less mercenaries. Don't want shadowheart to heal? You can spin up a generic cleric.
Well ye but of course the problem is that they'd be, you know, bland, personality-less and adding nothing to the story.
Though I think the current set of companions still need alot of work to make them more likable I'd still far prefer them over a bunch of mute henchmen. I don't think giving the current and future cast of companions more options for classes/combat roles can be that difficult to implement especially when stacked against how it would make the game just that much better.