Cut the ability to queue as a group in Frontline

[Canadane]

Unfortunately, half the mounts I don't own are only attainable from Frontline, no other pvp mode.

Yeah I feel that. They have some nifty mounts.
I do wish more people were motivated to win for them.
But I don't think culling the premade party option is a good idea still. I think it's good friends can play together.
My suggestion then is to fight fire with fire and find your own premade.