the cross-server LFG is a great idea. We can have a bigger pool of players for a party, and that's nice.

Attitude of players means nothing.
If they are rude, they will be rude with or without a LFG's feature. Simply, SE, has to give tools so we can defend against an impolite player.

LFG, autoteleport near/inside the instance, an improved world chat and LFparty (for raids, NM and quests). This is the way to go.
If some player doesn't wanna use a tool and lose 20 minutes searching a party, I don't care, but I don't wanna lose 20 minutes searching a party.