Dagger Storm: Grossly Overpowered
Pull skills such as Scorpion Wire will interrupt dagger storm.
Read: Playing to Win.
Guide: How to play a Mesmer in dungeons.
It doesn’t matter if it has half the recharge time, it’s incredibly situational. You need to be in a group of ranged characters with no AOE and no melee weapons who will keep firing at you no matter what and won’t bother to move out of range of your AOE. In any other situation you will be killed very quickly by any melee character. On the other hand thieves guild is reliable, always works, and gives you 2 allies that do respectable damage.
Using a bow is far better than dagger storm. No cooldown and you can do great damage while still being far away.
It isn’t easy to move out of dagger storm if you’re crippled and the thief isn’t standing still, and the range is greatly extended by the bounces. People also underestimate how easy it is to close with someone using dagger storm, especially if they’re moving away and the person trying to melee doesn’t have some kind of gap closer. Thieves are particularly well equipped to counter dagger storm, but most professions don’t have that luxury. Either of the “shadow return” abilities synergize well with DS by allowing you to escape when the duration is up. Dagger Storm is also a great way to punish ranged attackers in the short term without using it for the full duration. Futhermore, since the obvious counter to dagger storm is a melee attack, it is excellent for luring enemies into a caltrop field or towards friendly fire.
Thieves’ Guild is a reliable dueling asset (although personally I enjoy getting bonus procs off of enemy pets while they do nothing), but DS is a battlefield control asset, and not one to be taken lightly.
It’s incredibly easy to close with someone using dagger storm. Every class has a way to get there really quickly and screw the thief over unless they run away, like for example by dodging towards the thief or using one of the many gap closers a lot of classes have. Thieves have pathetic surviveability unless they stay mobile and keep stealth handy, which they can’t do with dagger storm.
You also forget that they’re 100% vulnerable to elementalist AOE, engineer grenades and jump shots (and i think the short ranged 3 and 4 rifle skills too), necromancer marks, hunter traps, and mesmer detonations.
Yes, you can lure enemies into fields with dagger storm, and yes you can punish ranged attackers for short bursts, but that’s a clever and tactical use of the skill. It’s not OP at all.