Note that there are other problems with Ranger (and I assume other classes', as well) powers. For example, there's a level 1 Encounter power that allows you to shift several squares and make an attack that does 2W+stat damage, and a level 3 Encounter power that allows you to make an attack that does 2W+stat damage... with no other bonus. Both have the same attack type (Str/Dex vs AC) and both do exactly the same damage (2W+Str/Dex). Both only fire a single attack. But the level 1 power has the additional benefit of letting you shift several squares before or after the attack, and the level 3 power has nothing special.
Oh, actually, wait... the level 3 power can only be used on your Hunter's Quarry, too. So not only is it weaker, it's got more restrictive targetting, too.
It's not just an editing problem, either, because the level 1 power is recommended for the Archer Ranger path, which means WotC honestly thought that it should be level 1 and the other power should be level 3.
The powers in question are Evasive Strike vs Shadow Wasp Strike.
The only reason to ever take SWS is because you want a second encounter power that does 2W damage; if you didn't take Evasive Strike at level 1, you can still pick it up at level 3 instead of one of the level 3 Encounter powers.