Wouldn't it be reasonable to assume that when things change, most probably change for the better, but some may change for the worse?
I doubt there has ever been a generation of mature adults who didn't look back with fond nostalgia on something they felt they had but then lost. That's human nature.
I agree with window boy that there were a lot of unsavory things in the past that I am really glad are gone. At the same time I reserve the right to feel nostalgic for certain other things if I so choose.
The problem with window boy's post was not that he was wrong about things that have changed for the better, but that he made the immediate assumption that what Rex was saying was that he missed those unsavory things. There was nothing in Rex's post to actually imply what window boy assumed. Therefore, his post had malicious intent.
A reasonable response might have been something like, 'what is it about the past that you miss?' From there a respectful dialogue could have followed. Who knows, maybe Rex would have shared some stories about his childhood that might have been interesting. Maybe forum dialogue might have been enriched.
In order to get to that place, though, one has to stop thinking that one knows everything or that one's own opinion (about whatever the topic is) is the only reasonable one. One has to think that perhaps somebody else might have an idea or a thought that could potentially be of benefit. To do that requires at least a little bit of humility, respect for others, and a desire to better oneself. To me it is more sad than it is triggering that window boy appears (to me, at least) to think that he has all the answers, and that his answers are inherently superior to those of others, rather than inquiring about the thoughts and ideas of others, thinking them through with an inquisitive/open mind, and then seeing whether there might be something of value there. If I am mistaken in this thought, I apologize.