It made sense to have the Water Elemental on a 3min CD before 4.0 changes, since it was a DPS boost.
Now, it is no longer a DPS boost in that sense, and it is a permanent pet without need to glyph.
Therefore, the 3min CD needs to be re-evaluated and compared to base talent skills of other classes, and it needs to be compared to pets of other classes.
You cannot take away the base talent ability of any other class by killing it, other than a frost mage.
As such, it seems redicilous to have to wait 3min to get it back.
Hence, comparing it with Mortal Strike, or any other base talent ability.
Yes it's true, demo locks have one that can be killed.
However, they have talents to get it back instantly, talents to reduce the cast time to 5secs, and it's a 6sec cast reduced by haste in the first place.
Any comparisons with Water Elemental and abilities other than base talent ones were unintentional.
They were also brought into this thread by others, not me.
I have simply tried to show that Bladestorm is not a good example.
As well, while it may be beneficial to have two instant re-summons, once you use it the first time and blow your Cold Snap, you have to wait 3min every other time.
And that's if you don't use Cold Snap before your pet dies the first time, otherwise it's just one re-summon.
So, unless we are talking about initial contact, with fresh CDs, having that 3min CD is much worse than being able to summon your pet with a 5,6 or 10 sec cast, modified by haste.