Its a big deal in PvP.

For PvE its not strictly neccesary persay, but can be interesting from a tactical point of view.  I've used it to skip past a clustered group of mob's aggro radius to a single one that was past them.  Sometimes is handy for pulling in conjunction with FD, or if you are in a group and the game tells you that you have no line of sight etc.

In general its just kind of fun.

But perhaps I'm missing something critical?

It's also a great way to move around in a dungeon by macro'ing it with FD.  (I'm almost positive the macro is listed in the macros post, but it bears mentioning here because of Hakuan's appropriately-titled Subject.)

/cast "Storm Stride"
/cast "Crescent Kick VI"
/cast "Feign Death III"

Essentially, this allows you to be 25 ft. away from a mob while FD and instantly "FD teleport" to him.  It's not 100% guaranteed and works less easily on roamers, I've noticed... but still quite valuable nonetheless.

Second major use (and in fact my primary use, esp in APW,) is I use it to macro out all of my pulling gear to dps gear.
It's not necessary, but like Simonson, I use it constantly for perfect positioning and insta-port after FD-pulling when the tank grabs aggro.

1. Pull mob.
2. Run past tank.
3. FD after tank establishes aggro, and immediately hit the macro. (listed below)
4. Hit it again once cooldowns refresh to activate Storm Stride.
5. Start debuffs/dps.

Macro:
/wear "DPS Helm"
/wear "DPS Arms"
/wear "DPS Weapon"
/wear "DPS Weapon 2"
...
/cast "Storm Stride"

The only reason in step 3 that I hit immediately after FD is that while it'll change out the weapons in combat, it won't change out armor while in combat.  (Someone correct me if wrong, please?)  Therefore, FD and immediately change out armor before the mob's AE attack puts you back in combat (the macro works even while 2s cooldown refreshes.)  Then, once the cooldown is gone, it's essentially just a Storm Stride attack to go into your normal opening attacks.

I actually use Storm Stride quite often.

-- Use it to get behind any mob and avoid any potential frontal damage the mob may do.
-- If a mob happens to be Graphically glitched you are guaranteed to teleport to where the mob actually is and not where it looks like it is.
-- I found that it can be quite useful on any encounter that tosses you up or back. If you use it quick you can actually teleport back to the mob before it knocks you to far back.
-- Almost always use it in a duel when someone tries to run around thinking they can get away from me!! They cant...

Those are the 3 things I most commonly use storm stride for... It does have many other uses however a lot of which have been posted here.