Hmm... I don't know what Lee Hall's motivation was for putting it in (he also wrote the movie, so the source is the same) but I think the way it comes across has a lot to do with each individual Billy. Some Billys are more lighthearted or serious than others, which can make that moment make more or less sense.
While Kiril was amazing, I don't think his leaving should deter anyone from following the show. I highly recommend people see the newest Billy, Alex, he's got seriously amazing dance technique, and a little more acrobatics than we've seen previously in the US Billys.