I think they are both quite rightly wearing the Balmoral Tartan, which is reserved for the Royal family: and rather than being 'cute' it is ideal for both to wear on such a DO occasion.

As others have mentioned, one should think here of a clan event, where everyone is wearing the same or variations on the same tartan-dress/hunting and so on.

There is something else here, often on this board one will see pictures, and read references to amazing and 'interesting' variants on highland dress. So there is a good argument for whilst not seeking to stiffle innovation: to look at the origins of kilt wearing, and possibly think where we are coming from.

Sadly, too often inspiration has come from little girl and other dancers, the excessive display of some bands, and the misplaced enthusiasm of certain kilt makers. With on occasion the result being nearer 'a costume' than highland dress.

James