First off, I strongly disagree with your claim that there are no good movies nowadays. I find myself enjoying modern movies just as much as I do older movies. I think your nostalgia might be blinding you to the genuinely good movies that are released today.
But on the subject of the OT, I think it was just as popular, if not more, before the prequels. It can’t be understated how much of a cultural force Star Wars was in the late 70’s and early 80’s. I doubt that the controversy surrounding the prequels increased its popularity much, given how popular it was already. Also, a lot of people here would disagree with you on the prequels being complete garbage. It’s not an objective thing at all.