I personally see that Sets should have unique styles than that of motifes(In imperial city the tel var armourer sells sets in your alliances style,I think it should be a distinct style made especially for a set)
If the set system was overhauled so there was a reason to wear seven (or more) pieces, and we weren't simply penalized for wearing extra pieces of a set. It would be a cool idea for sets to have unique visuals associated with them.
But, the way the system is designed now, with players wearing split pieces from different sets as the norm, it wouldn't make much sense.
But I really prefer wearing matching clothing, and adding "set-specific" styles to the mix would make that an even more difficult goal to pursue...
Not that it matters much. The powers that be are unlikely to waste their company money on paying designers to make styles they don't profit from. So, any new styles will be like the ones we have, craftable and dropping in new DLCs, or from events, or sold in the crown store, whatever.
What I DO really, really want in that regard... is a transmogrification system for master crafters, so we can reforde our swords, reswe our jerkins and recarve our staves into whatever style we'd like. For better visual goodieness!