While it's debatable about other long segments that have popped up on Sesame Street over the past 12 or so years, Monster Clubhouse didn't really jive with the rest of the show. Sesame Street always had a brisk pace, but Monster Clubhouse was totally insane. I mean, there's a reason why Yakko, Wakko, and Dot were locked up in a Watertower. It would have been a novel segment to alternate with Elmo's World, but they put it on the show at the wrong time of the episode, and it just didn't gel.
I recall most old schoolers hating it, if not as much as Elmo's World, then more.
I dug it, but it felt like it needed to be its own thing separate from Sesame Street.