Actually I answered that long ago, I gave you the exact explanation that applies to everyone in fact. I'm sure I'm wasting my time but I will go again.
A) because it's Star Wars and Star Wars is ongoing in the present day and into the future. It is therefore maintained in people's consciousness, both the good stuff and the bad stuff. It shouldn't actually be surprising in the least that on a forum such as this we still talk about the PT. If this were a forum about cars or something I might understand your bewilderment.
B) I'm not a Harry Potter fan, never was. I don't really care about it one way or another - that is key - I don't care about it. So if I happen to see a Harry Potter film that I was bored senseless by I'll say it was boring and I'll move on, never to mention it again. However, going into the PT, I was very much a Star Wars fan. When they were bad I noticed - more importantly I cared that they were bad. And if this leads you to again ask ''but why do you still complain all these years later'' I refer you back to point A. Because it comes up all the time. Why does it come up all the time? Because Star Wars films are still being made. And one person's comments feed another person's comments and so on and so on and so on. The very nature of a discussion forum.
I don't think I can make it clearer than this.