I'm very into the characters too, I think I'm just willing to accept a broader range of interpretations of characters. If a character acts in a way they haven't before I'm more likely to think it's a new development or dimension of the character than reflexively thinking OOC. If I'm going to read about the same characters for decades I want some new behaviors and reactions every now and then. People are wonderful for years...until they aren't and do something horrible and out of character. People are mostly crappy but maybe they have a redeeming quality that becomes apparent later on. I don't think they're not being true to character, they're just revealing another aspect of their character. I mean depending on how far back you want to go, we can find tons of traits or personality characteristics that weren't true to a given character...until they were introduced and became just that. Addition is a good thing and it usually results in change and added depth if done well imo.
Agreed that there should be a point to the hurdles. The old days of the villain of the month or "who could beat up who" just isn't interesting to me as an adult. That's one reason I'm ok with characters changing/growing/adding depth... if I'm going to ask for more complex stories I have to know that the old two dimensional good guy vs bad guy style of writing isn't going to work anymore, and I'm glad of that fact.