I played Ballista a lot back in XI; would I want it in FFXIV? I'm leaning towards "yes," but there are a few things that would have to be changed (or not, if you feel that way).

The main draw to a Ballista system for a lot would be that it is 2 teams, not 3. There were 3 "companies" (nations) in XI as well. Each match was one nation vs another. The odd nation out got auto-sorted. I fail to see why the devs won't or can't do this here.

The other thing is Ballista actually encouraged turtling (something I've seen players both here and during matches rage about). One death gave everyone in the Kill-shotters party in the immediate area the ability to "score." Obviously that means you don't want your teammates to die. What would happen for some time in a lot of matches is long, drawn-out staring matches between teams in the beginning, seeing which team would send over the sacrificial lamb to get ganked (not that that's how it always played out). All the while people spend time using the special emote to dig in the dirt for objects to score with if they did get Gatebreach and temporary items. The upside to this though would put more emphasis on staying together as a group (which players now have issues doing). Away from your party when they kill someone? You miss out on scoring opportunities. Kill someone out on your own? Grats, only you can make use of Gatebreach.

Seize as it stands now has some elements of Ballista (though Ballista could be participated in 3 PvE zones, making for some variety), but I would be lying if I said I wouldn't want to see the actual thing appear here.