But you have to look beyond that, because she's sharp and she knows what she's doing. She dresses everything up in bum jokes and general "off-kilter-ness", but there's more to it than that.
So what if she's not as po-faced and worthy as, say, Blackwall...? She provides a foil to the earnest nature of some of the other NPCs and a counterpoint to Varric's rather different Rogue character, and if only for that alone she's important.
More so though, she's a character very much more than the sum of her parts, she strikes me as some kind of weird genius - very astute and observant and good at reading a situation, but with neither the time, nature, or inclination to dress up anything in flowery language, or even serious language, but she gets results.
Seriously, spend some time with her, and you'll see - there's way more depth to her than it at first appears that there is and she is genuinely likeable, if a little spiky...!
On the subject of Sera being surprisingly savvy, I find that this is best demonstrated in some of her banter with Vivienne. She deliberately acts as uncouth as possible to highlight how ridiculous she thinks Vivi's posturing is (and by extension how most nobles behave). Everything from the way they treat their servants to how
seriously they take themselves and how important and essential they think they are to the world around them. That's all bullcrap and she knows it. She calls the Inquisitor a nickname because she's well aware that titles are something people wear to make themselves feel like they've got something on the people who
don't have titles.
Banter with Viv starts at 05:05:00.
Her banter with Solas is similarly insightful, especially on the nature and purpose of rebellion.
And that's the thing about Sera - she has no formal education, she's "book dumb" and streetwise, and she's so used to being called stupid that she's internalized that and uses it as a way to diminish herself (calls herself stupid during
In Hushed Whispers because she's being
poisoned to death by red lyrium and can't remember a poem, calls herself stupid for having feelings about the cookie story and her childhood...). It's sad, because she's her own kind of brilliant but she can't even recognize it because she's so accustomed to everyone dismissing her and calling her stupid.