I was talking with an unnamed kilt vendor last year at one of the local Highland Games.
I told her I had a utilikilt, but was now interested in getting a traditional kilt.

She said that it's "pretty common" for someone to start with a utilikilt - or other non-traditional kilt, and decide they like it so much they want to get a traditional style.
She said that for that reason, she (and supposedly other kilt vendors) sometimes referred to utilikilts as "training kilts."

Personally, I didn't think she was trying to be insulting with the term.