D/D is far from P/P – comparing the two is downright silly.
From a PvP standpoint, D/D’s big weakness is /D – The nerf to CnD and DD damage was a bit heavy handed, and DD’s inability to hit things that so much as sneeze while you’re launching the attack is frustrating. Lets also note that it only inflicts a 3s cripple, rather than the listed duration.
D/D can be strong in some situations – if there are pets/AI of any kind in your range, or static structures that can be hit, CnD is amazing – its a 6 init stealth (more realistically 4 init, since you’re probably running Infusion) , compared to D/P’s 9(7).
The problem is D/P ends up being much more versatile in the current meta (and most of the last few meta’s, tbh). The dual skill being condition focused while the rest of the set is clearly direct damage focused doesn’t help. Comparing it P/P is inaccurate tho – P/P is extremely poorly designed, while D/D just needs some minor tweaks.
Steal CD already got a big buff recently, and It’s in a fairly solid place right now – I still think steal could use some tweaking (untraited it’s meh, properly traited it’s amazing, the 2 extremes could use a bit of narrowing). a CD reduction isn’t necessary.
I’ve suggested in the past making CnD unblockable – People hate this idea because they hate thieves, but its not such a bad suggestion. All it does is allow a thief access to their defensive mechanics (invisiblity, SA traits) against a blocking opponent since none of the stealth attacks are unblockable – it doesn’t open up some insane world of hurt, it just allows a D/D thief access to stealth against block.