LvCaps promote new players who haven't had the opportunity to fully gear out their jobs yet, to be able to participate fairly in PvP.
If anyone ever actually played it, I would agree. But no one does. People don't PvP at low levels at all except in games where the whole thing is based around PvP. And then, you don't have a use for level caps either.

NOBODY does lv30-50 ballista. If you DO want to do it, there's still the diorama for that. But those caps should be removed from the official match schedule.