I'd say Utilikilts etc. qualify as kilts by virtue of having pleats at the back and overlapping front aprons. Bear in mind a kilt is just a type of skirt. Interestingly an English kilt maker (Midas) who produces mainly modern kilts covers the objection which some Scots would have to non-trad kilts by marketing his products as Kilts and Skirts for Men. Some of his products are box pleated all the way round while others have just two pleats at each side and none at the back for ease of sitting, and these do not meet the definition of kilts although I have found when wearing them that they are always perceived and accepted as kilts.