At least one of Menudo is still avoiding duty at Denny's - Ricky Martin. On the other tentacle, at least two of the New Kids have become actors - Mark Wahlberg is an adequate actor with a decent list of movie credits, and his brother Donny was really good as one of the main characters in Band Of Brothers.
In fact, a lot of singers turn out to be decent actors, as there's a big overlap in the skill set. Some examples: Frank Sinatra, Ronny Cox (Capt. Jellico), Madonna, James Darren, Nichelle Nichols...
I don't have a problem with celebs doing cameos, and before we get on our high horses about it, let's remember that Star Trek, The Next Generation had a very high level of celebrity cameos and guest shots - remember Mick Fleetwood in the fish suit, or Dr. Mae Jemison, or James Worthy as a very frightened looking Klingon?