I think Sherlock's absence on the show these days has a lot to do with 2 things.
1. The fact Jerry Nelson doesn't do a whole lot on the show anymore due to health reasons. He only performs the Count now once or twice a season. All his other charachters Simon Soundman, Herry Monster, Mumford, Biff, Fat Blue, Farley etc. are either only seen in inserted material from several years back, or have been written out of the show.
2.Another reason is because of all the newer charachters the show seems to focus on now. The writers seem to think they have more preschool appeal, and your'e less likely to see a storyline revolve around our old classic friends then you were in the 70's 80's and even 90's. Sad but true
The best thing is, we have 20+ years of Sherlock memories, and hopefully he will be on the DVD set, coming next month.