Are Quests Useful after 50?

[SirTroth]

After hitting 50, and with a lot of quests left (still haven't gotten out of Shimmersand and Iron Peak), I'm wondering if there's a purpose to doing the quests anymore. Since you no longer get any XP at 50, is there any other benefit for the quests? Or, should we just hold off until the next expansion, thereby making the XP useful again?

[Asangar]

Only to get the zone achievment for all quests, nothing more.

[Taluvan]

I can think of:

1) Money
2) Faction (Icewatch/Dragonslayers/Order of Mathos)
3) Story/Lore
4) Something to do while waiting instance/raid/battlefronts

Mostly money though.