I actually disagree. I was one of those who grew up with the PT and over the years I went from child who loved them to adult who knows they are terrible and would actually be ok with them being remade entirely. Meanwhile my appreciation of the OT increased.
I think that while nostalgia can taint ones perception just maturing in general can refine our perception of those things we grew up with.
I think the PT has a couple factors that make it able to be appreciated by some still: the story was good, the world building was good and other prequel era content outside the movies was good. The ST doesn't have any of those factors. The sequel trilogy only worsens over time and the attempts to expand with stuff like Resistance have only fallen flat. You can't build on a broken sinking foundation and expect the building to stand the test of time. The PT was a terrible house built on a good foundation so there is room to build good structures on that foundation.
20 years from now the ST will be forgotten, especially with all the other content being pumped out.