To me Indiana Jones had two paths it shoudl have taken.
1, End it at the trilogy
2. Make it like bond, where the actor changes and they continue the story (every 3-4 years or so a new one). There is so much that could have been told in the Indiana Jones universe.
But no they left the franchise dead for a couple decades or so to revive it for a weird move with Harrison Ford than again 10 year gap with Harrison Ford. They essentially put themselves in a hard spot where Harrison Ford is Indiana Jones.
So the only options now is, end the series, continue it with a new character not names indy, or reboot as it would be weird changing actors at this point considering indy is old now.
Harrison Ford as Indiana Jones is iconic and just about the only thing that gets Harrison Ford excited anymore. Crystal Skull was worth making just so I could see a set picture of him wearing the hat again.
I thought the next movie should have been a handoff to a new actor. Have two overlapping stories where Harrison Ford is finishing an adventure that a younger version of himself had decades earlier. Then they can just go ahead and keep making movies with the new actor as Indiana Jones. They don't seem to be doing that though, which is a pity.
It's not like it hasn't been done before. We're already up to 5 actors who have played Indiana Jones thanks to the River Phoenix flashback in The Last Crusade and The Young Indiana Jones Chronicles television series.
You've seen the two bad ones. Raiders of the Lost Ark and The Last Crusade are A+ films. Temple of Doom and Crystal Skull are like... D... or F.
None of the Indiana Jones sequels are great, but Temple of Doom is easily the best to me. Despite all its odd choices, it weirdly comes together well in the end. Spielberg was at his popcorn height in that movie though, so even Short Round and Willie couldn't completely derail him. The opening sequence alone is worth watching the movie for. I also thought Crystal Skull was fine right up until Marion showed up.
The Last Crusade is the one that I have no interest in ever seeing again. Spielberg wasn't even trying in that movie.