I think you make some excellent points, though technically Picard was diagnosed with Irrumodic (sp?) syndrome, which was taken to explain the time travel thing. Only further in was discovered what was actually happening.Difference between Geordi and Paris is that an interest in "writing" holonovels was an actual character trait of Tom's throughout the series. It's totally what he would be doing as an old man. His holonovels are probably really terrible, but very popular
What was Geordi writing? TNG technical manuals?
And Tuvok going nuts is like the natural conclusion for him. He's got all these buried anger issues. He's had all sorts of brain damage, and he's mind melded 10- too many times, with too many strange species.
Picard didn't actually go nuts. He was genuinely hopping through time. It was more a device so that his friends wouldn't believe him, to add a little conflict.
But, one point I did want to address that I liked about Endgame. The conclusions of many of the characters felt very natural from where they had been in the show. AGT was OK, but some felt a bit forced. I think the conflict between Worf and Riker probably stood out to me the most.
Weird to think about for me, but I see your point of view.