I'm a bit suprised by how many people honestly don't see the functionality of using Ranger Cures in groups. Seems to me the arguements are:
A: Swap to wands or use pots.
B: Use the blue bar.
Option A seems like it will take longer (IE: swap to a wand, cast, swap back to weapons), and given that wand whipping takes longer, animation wise, than casting.
Option B, however, means you don't have to spend the extra time swapping weapon sets during combat, and can often off-heal along side the cleric (depending on your build, tempests are going to be pretty focused at that moment and may only be able to self-heal).
As for a limited blue bar, that's what happens when you dump Wis. But even with a starting Wisdom of 12, a +2 tome, and a +5 wis item, my AA has a base sp pool of 341 at lvl 12. If I'm not XP farming, I can bump it to a sustained 441 with a PoPX. Hardly limited. Not nearly as deep as a cleric, but more than enough to throw buffs (Barkskin, Resists and Protections) to a full party and still off-heal and sustain those buffs during a raid (VoN5/6) with minimal Shrine use.
Fact is, it's all in how you play, and while Devotion enhancements, items and other feats/clickies help, to be truly useful you have to WANT to use them. In the end, there's no right way, there's just different ways, and I personally prefer mine. Not saying others are worse, nor that mine is better. Just different, and beneficial for different reasons.