Everything you said is right. But I could do the same as a companion main and get some story on top.
I mean I did the same in divinity. I could play a mercenary or depending on the class I want to play, pick a corresponding origin. I can skill the character to my liking and can behave as I like (good/evil) ect. But I will get more story, more quests, more dialog and personal stuff on top.
So I quit my only non origin run before the town. No point in playing. It felt as if I am missing out on something. (Without origin characters I maybe wouldn't have this issue as there is nothing to miss then..

)
With strict classes races, subraces and so on I doubt that here will be a companion for each subrace / class ... so back to the mercenary.