I guess I saw only Raiders as a kid, so it was only in the later years that I decided to fully watch all Indy movies. When you see them back to back, without years of nostalgia to protect the first three, the fourth one isn't THAT bad. Sure, it had its flaws but I found it kept the tone of the first three movies, it felt like people doing it knew what the other three movies were all about. Again, it didn't come out great but it actually felt a continuation of the character and the style of the older movies, which had silly parts as well, maybe not nuking-the-fridge silly but silly nevertheless (like Indy's father taking down a plane with birds).
This is however unlike Star Wars, where the story can go on after years with new characters. This is all about Indy and so you're stuck with an old Indy and it has to happens in the '60s because of his age. With such constrictions, a reboot it's better, and since Harrison Ford is irrepleaceable... just leave it alone, like Ghostbusters