We simply don't have enough information on the hirelings. But yes, it does appear as if Larian really doesn't want us using them, making their appearance not customizable and using 'temporary' makes it seem like they're intentionally designing them to be a last resort situation.
The way to get people to use companions is to make better companions. They put all this effort into unlikeable 2d jerks and then try to strong arm players into taking them along? Why not just only have hirelings and fully customisable party members if you can’t make anything better?
