You know, if there's one thing the writers have become masters at, it's phasing out characters to the point where you're not even sure if they're on the show anymore. Like, most of the time they do it so gradually that you don't even notice.
Well, over the years, the show has had scores of recurring characters, many of whom don't/didn't appear in every episode, and back in the old days there were about 130 hour-long episodes a season, making it a little harder to really know if a character was still on.
For some reason, during season 25, I noticed that Bruno didn't seem to be around anymore, and didn't really notice the lack of any other characters. And it seems his appearances in his heyday were few and far between (for a long time the number of episodes/inserts I knew he was in could probably be counted on one hand - and the wiki had info on plenty of '80s episodes, even if that number has greatly expanded - and the amount of known episodes with Bruno is still kinda small even if it has grown). I didn't really notice Richard Hunt's characters being reduced to inserts (but at the time I didn't know what Sesame Street characters Richard Hunt performed - I kid you not, the only recurring character I knew he performed was "one of the Monotones", having seen it in the performer listings of the tenth anniversary album. At at the time I didn't know who Little Jerry and the Monotones were or what they looked like or if I'd seen them before). Of course I think inserts starring Forgetful Jones, Gladys the Cow, and Placedo Flamingo were frequently airing.
But then in season 30, I actually noticed many characters not appearing anymore, or at least being seen a lot less than before, whether in new material or old inserts. And I'm not just talking about "around the corner" characters. Of course when season 30 aired, I was able to watch the show every day (before, when I had a babysitter, I wasn't always able to watch whatever I wanted to watch, so my Sesame Street viewing was a little limited), but I noticed that season we barely saw (if at all) Kermit, Guy Smiley, Sherlock Hemlock, Lefty the Salesman, Simon Soundman, Biff and Sully, Grundgetta, or Forgetful Jones, but I had recalled seeing them in what season 29 episodes I caught before season 30 (and then when some season 29 episodes aired during pledge drive season and again when the "Slimey to the moon" storyarc was rerun in the weeks before season 31 premiered, I saw a lot of these characters again, some quite a bit).