Quote Originally Posted by yukikaze_yanagi View Post
because nostalgia have the problem to make everything look good when in reality they were or are bad. It's not a problem of "stop liking what i don't like"
But good and bad are entirely subjective; you can't objectivelysay something was 'bad' or 'good' unless you are getting into some fairly extreme examples. Some people like grinds that take months if not years. Some people hate them. No amount of nostalgia can make you believe that you really enjoyed doing something when you actually really hated it at the time. If you hated doing something at the time you can later think 'In hindsight it wasn't that bad' but it will never make you think 'In hindsight I really enjoyed it'.

Quote Originally Posted by Pandastirfry View Post
Because looking back fondly on past experiences or items is the very definition of nostalgia? That might be why?

The problem is that when you let that nostalgia blind you to valid criticisms of what you are fondly remembering that it becomes a bad thing.
That definition of Nostalgia is correct, but it is being used here to imply people's memories are distorted by it. If person A says 'I liked something' person B is wrong to say 'You didn't like it at all. That's just nostalgia'.