I've played ranged tanks in other MMO's and there are some perks. I'll list them out. I'm also assuming I wouldn't go bard for this case. That limits too many cross class skills. It wouldn't be the first time I've gone end game without an "advanced class" and made it work.

Pros
Draw enemies in locally to you from a distance. Sometimes, someone will go rush in as a DPS and suddenly it's that much harder to aggro because I have to chase the damn things down. With range, you can aggro from afar, meaning less chasing and more meatshielding. This is probably my biggest pet peeve right now as a tank. Let me aggro first dammit, and stop rushing in.
Ranged dps over time. Usually the best way to go, so you can save MP or whatever system a game has for healing and abilities. It just means simpler management of the field.
Annoying people in pvp. Nothing amuses me more than to hit someone from afar, or to be a tank healer and not be squished.