Specifically, we're waiting to hear from Taelorn to chime in on how critical he feels these non-period, non-region ships are to the game. They're not necessarily like galleons -- galleons are considered "OMG you can't have a pirate game without galleons!" type ships. Archipelago frigates? ...not so sure.
Also, there are limitations as to what strengths and weaknesses the game engine can model. A prime example of this is mortar vessels such as the
Hielperinden: not only can we not currently model its main strength -- bombarding shore emplacements -- but we cannot model its awkward handling or sensitivity to sea conditions. There are similar problems there with the archipelago frigates; historically they'd be useful only in very calm seas due to their low freeboard. Right now we don't have changing sea conditions that provide this obvious self-balancing tradeoff.