I own many kilts and many hats but not all of them look good together. The two styles that I just don't think work with the kilt are my fedoras and my bowler. I've tried it and the almost unanimous decision was great hat, great kilt but not together. Honestly it just looked a bit goofy. Granted the cowboy hat doesn't do much for a kilt in my opinion either (Sorry Jaime)

I think the problem with the bowler (or the fedora for that matter) is when you see the hat you picture the outfit that goes with it. A kilt isn't what you picture.