I think this manga's goal is to make neets who would read it, feel guilty, or ashamed. And for the others to pity them.
Feel guilty toward their family, their friends, their past selves and even society as a whole.
The tone is comedy, but the subtext is that, at the moment, she's worthless.
Literally the opposite, I'm pretty sure. I'm going to preface and say I've been in Neeko's shoes for most of my adult life(hell I'm barely a year older than her), it's scary how much that this manga has reflected literal events that have happened in my life. My read has been similar to two other fantastic works about social anxiety--Welcome to the NHK and (early-mid)Watamote--it's almost autobiographical in a sense. Yeah, they're comedies, and yes they're not afraid to poke at their protagonist, but it comes from a place of knowing and understanding. Last chapter, with Neeko's self-destructive nostalgia fit for example, is an aspect that even works focusing on neets rarely address, it's something I've done before. This last chapter, if you're taking it from the family's view I don't really know what to say. It's another thing that's happened personally to me--trying to take a step to better yourself in some way, then having your family come, misinterpret that initiative, and pressure you into doing things you're not ready to do until you just break down and end up pissing away whatever initiative you had. The various bouts of vapid indulgent selfishness, only to beat herself up for them after? Yeah that's legit too.
Now, why is Neeko perceived in such a negative way? Because we see things through her perspective, and she has close to no self-esteem. She feels guilty about being a burden to her family, about being developmentally behind her peers, about failing her past self(which speaking of in that flashback? Neeko's aspirations being completely vague even back then? That's the real shit right there). It reflects in the narration and the her actions. The subtext isn't really that she's worthless, its that she thinks she's worthless when that's not really the case.
I really like this work in a lot of ways because it's one of the very few times I've really seen ~my~ experiences put to a page. I don't really think it's been a comedy much either, there are certainly comedic moments and by and large it's more light-hearted than something like My Lesbian Experience, but that's not a bad thing either.