Ahhh... I see your point, but I don't think Neville's had it that bad.

The way I see it, he's having a better chance with the girls at Hogwarts than I think he would at home (at least Hermione and Ginny treat him really nice), he's got good friends (Ron and Harry are sticking up for him at the very beginning... remember in P/SS, when Ron and Neville take on Malfoy, Crabbe and Goyle? And all the times Ron and Harry encourage Neville?)... he is scared of Snape, but he's almost as scared of his gran (he didn't want her to show up as the boggart, either

)... I think Neville's home life is really pretty sad... he's constantly having to live up to a glorified reality (Frank Longbottom was probably a great wizard, but you know how it is, Neville's gran probably looks at Frank and sees all the good and none of the bad, so Neville's having to live up to that), I'm sure his gran really adores Neville, but she is hard to take... at school, he has Snape but he also has people who encourage him and make him stronger... but I don't think he'd want to stick around Hogwarts if he had to without Harry, Ron, Hermione and Ginny around...
When Harry thinks if he had to pick anyone out of the DA to come with him, it wouldn't be Neville, Luna or Ginny... Well, I think that's a writing tactic J.K. Rowling is using... She's depending on us not giving Neville, Luna or Ginny the credit they deserve, based on their first impressions. Rowling seems to want us to think of Ginny as the shy, dependant baby sister (she's obviously not, but even in OotP, Harry just notices late in the book that she's not as quiet as she used to be). Rowling wants us to think of Luna as the spacey ditz (she's obviously not, she's the one who kept her wits about her in the heat of battle). And she wants us to see Neville as the loveable dunce who is only good at Herbology (he's obviously not... especially in OotP, he is able to hold his own pretty durn good)
When we meet someone, if they come across as a shy baby-sister, or a spacey ditz, or a loveable dunce, that's how we see them even after they've proven to be otherwise. That's what Harry's doing (he's even told flat-out that Ginny may be small, but she has exceptional powers, by Fred and George, who don't give out compliments about their siblings too willingly.) And I think Rowling's doing that on purpose so that it seems to come out of the blue when they do something good, like Quirrell being the bad guy, or Lupin being a werewolf (we had the hints, but didn't realize until after the fact that that's what they were).