She mellows, but has her moments. She's actually pretty horrible in the fifth book, though.

But I do think it's a bit of a guard. I also think Hermione and Ron are actually very similar in that they have their fall backs -- Ron being snarky, Hermione being logical - and don't always consider other people's feelings, since they know why they're being like that. You may have inspired an entry, actually...

ETA: Also, it occurs to me that Hermione's a bit like Emma from P&P. Emma also totally means well, yet gets so caught up in her ideas of what's best for everyone, she loses sight of what matters and what might truly be best for others.