See, the problem is that you think because you didn't watch it, that means nobody watched it. But let me assure you that Friends has a quite large and nostalgically devoted fan base, and it is absolutely part of our pop cultural heritage.
I honestly don't know how anyone could conclude that from what I wrote, nor how you might conclude that, about me.
I'm keenly aware of how popular the show was - my wife was a fan. I considered buying her the series once, as a present. I never watched much TV before meeting her, I didn't own a TV in the 80's, rarely watched anything on TV in the 90's except movies, and I never saw shows like Dallas or Miami Vice or The Cosby Show - but I know who JR Ewing, Sonny and Tubbs and The Huxtables were. Ditto 90's shows.
I simply do NOT get an outpouring of five days of news broadcasts about the death of a member of a show that ended twenty years ago. I'm pretty sure I will see more, today. I think if he had NOT died but simply vanished into obscurity, no one would be asking, hey whatever happened to Matthew Perry? If Michael Richards - Cosmo Kramer - passed away, would it generate the same sentiment, for a week?
Because it just happens that cast members of popular shows - often, that's the peak of their career, and many years later, people have largely forgotten them. Like Richards. We may have fond memories of them, in that role, but after that role, fans often ignore them. Ditto rock stars - we fondly remember them and are disappointed when they die young - but we just don't make much of a fuss if they've been largely off the screen or radio for many years.