I think even more than mailtools/fileservs and punters, my favorite thing about AOL progz was just being more expressive. When you hung out in TeenPoolParty13, you could be extra cool by sending text that was wavy, or mixed colors, or different sizes, fonts, etc when the actual UI didn't let you use that many options. But it let you embed HTML (and I guess UTF) so with a prog you could be more expressive, or just plain weird.

I've never forgotten how progz, Geocities, and MySpace all showed that people want to express their individuality and experiment if you give them the chance. But the boring commercialism of the 2010s internet killed the user's ability to be special.