Rogue problems are threefold and have always been tied to three things:
Mobility - only melee class lacking a base gap closer (also paladins I guess). Shadowstep was major reason for sub being the rogue pvp tree for a long time. Combined with the reduction of our snare to 50%, rogues now face the problem of being kitable and lacking tools to get back in range or keep the target in range. One or the other would be nice, both would be excellent.
Burst - rogue burst is questionable at best due to how they generate damage. Lots of damage from passive sources means that you need high uptime on a target to put out real pressure. It also means that it's very difficult to establish kill windows. Old sub had burst in the form of ambush and backstab (which had baked in crit modifiers so they consistently hit for relatively large numbers). Baked in crit is gone. Other trees lack anything other than envenom/evis and not enough damage is baked into those abilities. Combined with mobility this is a large problem. Do I think we need Vanilla one shots or Cata vial ambush level burst - no. But I do think rogues need to have damage rolled into active sources and away from passive sources allowing for kill windows and burst from resource pooling.
Timer reliance - rogues with timers have always been too powerful and without have always been super vulnerable. The problem right now is that the timers are less powerful but the vulnerability has remained. Shorter timer lengths combined with the removal of prep entirely would be my personal solution to this, but it's open to debate.
On a side note, the over saturation of CC abilities has become an issue. Every class offers a ton of control now, usually with little to no cost in output. Rogues are still operating under an old model of damage sacrificed for control. This has had a side effect of making rogues become less powerful in relation to other classes simply because they haven't been updated to the current game model.