The original racial sets I agree should stay racial, even if the relation they have to their races' actual cultures seem dubious at best. It's still the case that all the promotions and advertisements featuring these races show them in their race-specific starter gear, so those items really do have a strong racial association to them from the get-go.

The hempen sets, however... I don't have an issue with spreading these around. Perhaps the split variants could be named things like "Highlander Chemise" or "Elezen Underpants" to keep the original racial source in memory.

That said, I can't decide whether seeing a Lala girl decked out in Highlander bondage undies would be more hilarious or disturbing...