I can pass this by the devs, regarding the quantity of mana, but again, we're talking about efficiency and saying it should be better. Of course you want more mana, but to say that Water Shield should be pushing toward some sort of complete replenishment might be too much. The group-utility issue is probably not something the devs are concerned with, as the intention is to benefit the Shaman themselves.
Q u o t e:
Water Shield is nice but doesn't provide enough mana and doesn't provide anything when you're not getting hit!
I don't think the devs ever suggested it should have group utility. When taking your example, however, you are assuming the Shaman is healing or range dps'ing, which may not be in all cases. A Shaman switching roles and doing melee damage is going to see effect from this.
Q u o t e:
Lightning Shield provides no benefit in group settings.
In further replies, he went on to say:
The recent clearcasting change is a change to support mana-efficiency. The devs aren't opposed to giving mana-regen where needed, but it can also be dealt with through itemization and not just core, class changes. You also haven't addressed the point of Shaman being able to do more OOM than a Priest or Mage.
Fair enough and I get your and others point [that Ele and Resto Shaman can only DPS with their low-DPS caster weapons when OOM]. You phrased it well. ;)
Again, there have been some concern from the devs before as to mana-efficiency, so it's something that has been adjusted before and could very well be again.
My usual disclaimer applies: I haven't played a Shaman past 20, so I really have no idea what they play like. Is mana efficiency a big issue? Do you feel like you have it harder when OOM than clothies do? May I refer to a manaless Shaman as a "Shooman?"