I've enjoyed them myself too, and I still use things like IRC on a daily basis. The two impluses I see to get federation to a larger market share are A) to 'save' people from the platforms they're currently stuck on, but also B) get rid of, or at least diminish, their network effects.
You could argue maybe A) won't work or isn't possible or needed, but I feel B) myself a lot. For example I meet someone and want to talk to them, but it's likely they might suggest we chat via Skype or Discord or something like that, and if I don't want to use that service I'm often out of luck.
That, personally, is what bothers me the most - that network effects seem inherently anti-competitive because they force me to use a platform I wouldn't otherwise want to use, only because they purposefully make their software unable to communicate with competing platforms.
For all of the open protocols and specifications we have from HTTP to TLS to HTML and literally one thousand others, we just re-use them over and over to create closed systems that can't talk to each other, which feels like going backwards. Sure it's great all of our computers speak TCP, UDP, TLS, HTTP, and so on. But they don't all speak iMessage, Zoom, Skype, Discord, Reddit, Twitter, Mastdodon, Matrix, Slack, etc etc. I still feel constantly locked-in to all of these platforms just when I want to communicate to someone that happens to be on it, and the area is certainly not progressing because the fight to gain this huge market share of users is never-ending.
Ideally, that is what I would love to end via federation. If I could actually use some type of FOSS and open protocol, and actually talk to any other person I wanted to with it, and I wasn't forced to use a certain platform, service, company, and give them all of my data in the process. I don't see any way for this to be achieved, but I can always dream.