To those interested in learning more about this perception-morphing phenomenon, read this (free) ebook.
https://www.secrethistoryofstarwars.com/book.html
It is based largely on GL's own words. You'll also see how the Expanded Universe and many other factors influenced the direction of the sequels. You will learn how, over the years, the direction of the story has changed.
Sure, it's opinionated, and it may even offend some, but if you want to know how far things have deviated from 1977, and if want to understand how imperfect and malleable the creative process is, then this is your book.
In a nutshell, the original Star Wars (before it was called A New Hope) was a simple good-versus-evil story, and not about the tragedy of Anakin. When ESB hit in 1980, it confined what was once the open-ended, self-contained story of ANH into a smaller world by tying the protagonists with the main villain(amongst other things).
In the space of those 16 years from ROTJ to TPM, the PT's plot could have gone either way. People change over time, and GL wasn't the hungry, driven 30-something anymore. The PT has definitely changed how one 'should' view the OT, but it doesn't mean that you have to adopt it wholesale.
To those who love everything SW, please continue doing so, but I think that this book settles the score best, as to why some folks were disappointed with the direction of the franchise.
As for me, I tend to prefer the original iterations of good ideas, so McQuarrie's artwork and SW 1977 are the core of what SW is to me. Some bits of TPM(my favorite in the PT) looked promising, which sadly weren't expanded upon, while some bad elements were dragged on too far into ROTS.