Similarly, I always prided myself on making friends with mature, wholesome people. Not necessarily mature in the same risk-free way that I was/am, but just intelligent and thoughtful. Therefore, isn't it understandable and inoffensive that I'm bothered when my friends talk about how much they've changed over the years, and even more so when they repudiate their former selves? I liked them then, and I liked them for positive reasons that haven't gone away, and those characteristics are still what I see when I look at them, so to me they haven't changed much. And they especially have nothing to be ashamed about, with regard to who they were.
So, yeah, change is a good thing, if you want, but if you notice that I might frown a little instead of smile a lot when you tell me how much you've changed, that's why. It's not just nostalgia.