The issue with pulling hate doesn't come from the fact that rangers go down in 3 hits. They do by the way. :P With a good healer any job can remain standing (I have a number of deathless Ixions to stand testament to that).

The problem with pulling hate is that you are moving the monster you fight (and this is why your defensive-reflex JA would only be useful for identifying the sweet spot... which you could do on your own pretty quickly). Melee get really angry when you move their monster though ... they can't hit it any more and they lose their tp when they try to ws as the monster runs away. Mages also hate it because they have to reposition and you might be pushing your entire ally into aggro radius of other things or sending a nasty aoe their way if you're standing next to the mages (kind of like people get annoyed when blms pull hate). I think the real fix for this problem is going to have to be reducing the amount of enmity a ranged attack creates or programming the monster's AI in such a way that someone from far away can take more hate than a close range DD without moving the monster (basically even though your hate would be higher than the tank's hate, you would have to hit a certain cap above and beyond the normal one before the monster would move away from what it was already attacking). You might be able to make a feature like that into a job trait which is ranger specific (otherwise I see BLMs abusing that quite a bit).

I like the sniper job trait, that sounds neat. I don't think many people would use hawkeye shot instead of double shot though... you would be lowering your dps by doing so. If it were on it's own timer I would definitely use it though.