I have kilts with straps and without.
A couple of second-hald kilts I bought are far too big round the waist, so the straps are no use. A well-adjusted leather belt is quite sufficient.

Only once has a kilt thus worn come undone; the kilt pin caught on someone else's clothes while dancing, and the whole thing was got unwrapped!
No, I was dressed in the usual way for dancing, not regimental.

Martin,
in Grenoble, France