I'm fucking 38. I was finishing high school and I didn't see TPM until months after it dropped. I'd mostly lost interest in Star Wars at that point, far more focused on starting college. Even then I was aware of the reactions from my peers and was given a lot of pressure to see it. People didn't like absolutely everything about it, and yes some people didn't like it at all, but overall I witnessed it treated as a spectacle that people were excited about, if for the visuals than any other reason. It wasn't until AOTCs that I felt more of a shift towards hating the prequels, mostly because the setup for the war was pretty ridiculous. People still liked the spectacle but the shitty romance seemed like a poison pill. It was a large chunk of the movie that was just painful to watch and killed the mood. By ROTS the general disquiet had turned to general griping and the jokes were no longer in good fun, instead just being mean. Ironically ROTS was better received from critics, largely for not being AOTCs.
I did finally see TPM in the theater, a friend had to drag me out to see AOTCs, and I never bothered seeing ROTS on the big screen. I didn't really get back into Star Wars until well into TCWs which surprised me for how it rehabilitated the prequels.
Set aside the prequels for a moment. You know what I saw really getting shit on? The Special Edition. A lot of what was added into the movie seemed gratuitous and silly, failing to add anything of real value. Lucas was fucking with people's nostalgia and they turned on him harder with each "new" release of a beloved old film. Without that I suspect the prequels may have been largely accepted, albeit not as loved as the originals. Mostly considered harmless and perhaps a bit forgettable beyond the, yes, spectacle. But Lucas torched every ounce of goodwill he had with large swaths of the fandom. Some still haven't forgiven him.