Yeah after Return of the Jedi I think general audiences were done with it. There wasn’t anything new coming out in theaters and the hype died down. Among true fans the RPG and the Thrawn trilogy started a small revival that endured through books, comics, and video games.

However I don’t think the prequels were ever “cool” at the time. People watched them because they were big budget spectacle and because of the Star Wars name, but I remember that they were not taken seriously. Jar Jar, kid Anakin, then teen Anakin in AotC were heavily mocked. So was the dialogue in all three.

Certain aspects like Darth Maul were definitely cool and had an outsized influence in merchandise. The EU continued booming with books, comics, and video games, but those were still largely limited to true fans and gamers.

I still don’t think it’s necessarily “cool” now. It’s more that it just lingers everywhere and has merchandise everywhere. There’s nothing particularly youthful about it; the same boomers that post minion memes on facebook also post/buy Baby Yoda stuff. There will probably never be the same level of hype there was during 1977.