With Usenet, if you join, say, comp.ai, you know that (spam aside) you're just getting AI stuff. Same for comp.linux, comp.lang.c++, or whatever. There's something to be said for the topic hierarchy there.
I see a place for both ActivityPub and Usenet, personally. Although, again, acknowledging that somebody could probably in principle build the Usenet style experience on top of ActivityPub. But as far as I know, that part doesn't exist today. If it does, somebody please let me know.
Interestingly, this seems to be amongst the most controversial aspects; some people _hate_ it.
Personally, I was only quite dimly aware that Twitter had an algorithm now, like a common Facebook; until Musk ruined it I generally only really used Twitter via Tweetbot, so was getting a time-based feed anyway. So Mastodon was just what I was used to anyway. But more people than I expected actually liked the Twitter algorithm, and couldn't cope with Mastodon's lack of magic ML stuff at all.
Yes, having images available within mastodon is nice - that was always clunky with usenet.