To say you are to old for Sesame Street is to say your too old for entertainment. Yeah, there are some shows that noone over the age of 5 should watch, but thats cause they are ****ty shows(ie: Telletubies, Barney, etc) and insult kid's intelligence.
As for being a 'completist'...I havent watched Sesame really since the late 80's...BUT! I keep up, through specials, catching it on tv now and again, dvds, etc.
To say you cant get into it because you missed thousands of episodes is bull. Thats the beauty of Sesame...its here to last, and has been the only consistently broadcast Muppet show for the last 30+ years. I myself havent been able to get Sesame with my antenna for years...and have probably missed out on a lot of moments. But fromt he chemistry with Telly, Baby Bear, Zoe, Bert, Ernie, Cookie, Oscar, and yes even Elmo...it is definately worth
seeing out at least some of the specials. But there is no real evolving storyline or canon, so its easy to just check out episodes here and there. I HIGHLY reccomend Elmopalooza...very fresh and great.(It even has the yip yip Sesame Martians on Conan O'Brien!)
I just have to laugh at Muppet fans who pass off Sesame(or Bear for that matter), as Sesame contains some of the greatest Muppets and performers of our time. Where you think the new Oz(Eric Jaccobson) got big?
At any rate, I hope Sesame Street is shown forever...as it is one of the few remaining kids shows worth watching...along with containing some GREAT chemistry and entertainment.(err, at least on the Muppet parts, never liked the cartoons)
To deny Sesame is to deny being a TRUE Muppet fan.