I already said that above. (and got a few facepalms for it). Alexia doesn't help advance the plot and if it wasn't for the Alexia deuteragonist part, the game would be in Act 3.if you have to go this far, then you could also ask if alexia working has any benefit at all. her work is never important for the story as everything she does is optional.
the library gives a bit history on the chaos side of things.
the forge is mainly just greyhide backstory and a little bit castle upkeep.
the maid job is jezera and her politics.
the breeding pit is monster lore.
so there is really nothing of "importance" going on. especially since even if alexia would learn something of value for the plot, like as a maid for jezera, we don't even see her instructing things to rowan in that regard. we hardly see them interact outside of romantic/sexy stuff in general.
but do you play games like SoC for the main plot only? maybe it really captivated you. who knows? but i doubt that even 10% of players think like that. most want to see their favorite character in scenes. the more the better.
and in regards of worldbuilding: of course the tavern helps with that. with rowan we mostly get to see the heart of the military might of the twins. it's interesting to see how the forces of chaos deal with the outliers of the kingdoms.
generally speaking every character addition to a story allows for worldbuilding.
Would the game be as successful? Probably not. But the plot would be moving.