Well, I certainly do appreciate your reading more anger and resentment into my position than exists. And I'm not advocating "chang[ing] the story line," but it's difficult for me to see what sort of interesting story they are going to tell in a hypothetical fifth film when Indy is tied down to a happy life back home. The past is past, yes, but that only dictates the future so much. The thing is, what other recyclings of sidekick options are left at this point? Marion, the old flame, has been done twice. We've had the kid, the mentor, the father, the traitorous friend, the loyal friend, the dotty old professor, the femme fatale, and the society dame. The only one that might have something new to offer is the son - although a straight-up protege without the explicit fatherhood connection would potentially be more interesting.
Basic idea is this: a character who has what he wants is inherently less interesting than a character who doesn't. So I'm not going to treat Indy like my friend who I hope gets what he wants. I want him to get put through emotional hell and need to rise above it, to have gotten what he realized he was missing and then have that taken away from him, so that he needs to rebuild meaning into his life in whatever way he can. And considering the obsessions of the series, that probably means combining his vocation with his extracurricular activities, which is to say, in the training of a protege, and in finally becoming the mentor himself, in the field, and not merely in the classroom.
And, of course, these aren't fully formed thoughts. I'm not claiming to have found the definitively correct way of telling the story. But I do think it's probably better than one in which nothing has truly happened between the fourth and fifth films.