He went right out of fashion by the mid eighties until his Glastonbury performance in 2000. . Never out of fashion with me I hasten to add . That Glastonbury show was one of my "I was there" moments. There I Just had to find an excuse to fit that one in!!
He certainly became less fashionable, if that's the right word. He returned to no1 singles with Let's Dance but personally I don't like the sequence that began with that album. I think he felt the urge to sort of purge himself with his subsequent Tin Machine phase, back-to-basic rocks and touring in a van to small venues. Some mocked him at the time for that, but I say good for him. He's David Bowie, he should do whatever he feels like!
Many also look askance at his 90s phase but I really like it, as I generally do all his subsequent work.
I think you're right in that he had fewer big hit singles than most probably assume. I suppose that perception is partly a consequence of how big a cultural presence and influence he was, and still is.
If you were at Glasto 2000 you don't need an excuse to mention it, just go ahead. I would.