If we examine the offensive cooldowns available to the two premier PvE raiding specs, it's clear that combat has a significant advantage. Mutilate's most potent CD is Vanish, which is actually only used to activate the Overkill buff. Overkill provides a grand total of 60 energy over its entire duration, which is about a 3.3% increase in overall energy regeneration. That's only one extra Mutilate every three minutes, and it also forces the mutilate rogue to sacrifice one their defensive cooldowns to activate it. Cold Blood gives mutilate some reliable burst, but with critical strike rates exceeding 60% in higher level gear, the boost is negligible. Cold Blood actually does nothing to boost our DPS if our attack was going to crit anyway, since there's no way to save it to convert a non-crit into a crit.
Combat, on the other hand, possesses three of the most potent cooldowns of any class or spec. Adrenaline Rush, when used on cooldown, provides 188 extra energy, which is an 8% increase in passive energy regeneration if used as often as possible. With the same CD as Vanish, and no sacrifice of a defensive CD, this one ability alone completely wrecks all of mutilate's burst techniques. We also have Blade Flurry, which allows us to nearly double our damage for 12% of a dual-target fight and allows us to double our AoE damage as well. That's on top of the bonus haste it provides, which is a pretty sizable DPS boost by itself. Killing Spree provides us with combat's final DPS CD, which deals massive damage and is on a short enough cooldown that it can be used to guarantee high burst DPS in times of need, like on a crucial add spawn.
What I would like to see is a softening of our cooldowns into a more leveled curve than the current spikiness that they currently exhibit. Imagine if Adrenaline Rush boosted our energy regeneration by 50% for 15 seconds, but was available every 90 seconds. It would still provide a sizeable DPS increase on demand, but would also make our DPS over a fight much smoother overall, which is a good thing for balance. Cold Blood could use the same treatment, such as a window of 10% extra crit or 30% stronger crits. That would give it usefulness in any situation, and would give mutilate a much better tool to use to provide extra DPS when necessary.
All rogues share the same set of defensive cooldowns, which allow us to mitigate large amounts of damage or completely avoid many effects altogether. We have Evasion, which provides us with a significant amount of physical avoidance (both melee and hunter-based), and gives us a short pocket of protection where it is very hard for our opponents to do much of anything to us. We have Sprint to keep us close to our targets, though it suffers from the same long cooldown problem as Evasion. Rogues are stuck relying on one of these abilities to save us or let us catch up to our opponents, or else we're really dead in the water. It's the reason that every single PvP spec includes Preparation, since these CDs are literally our only shot at performing at the necessary level.
We also have Cloak of Shadows, which makes us nearly immune to magic for the duration, and it will be a full 100% resistance in Cataclysm as well. I feel that Cloak of Shadows is actually close to where our cooldowns should be, with a short overall duration and a relatively short cooldown that will allow us to use it multiple times per encounter. The ability of a rogue to use a short duration, short cooldown ability to handle various aspects of a fight should be the design paradigm we're moving to. It keeps us active all of the time and reduces the overpowered factor that comes from abilities that are too strong. Feint is a great example, as it provides moderate damage protection at the cost of energy, and we're not invincible while it's active.
One possible solution
Imagine if Gouge and Blind were combined into a new move: Blouge. It would be a 30-second cooldown, with a 20-yard range, and it would incapacitate our target for 6 seconds. By making it useable more often, it becomes more of a clutch decision to use, and less of a problem if it was quickly trinketed or accidentally broken. Overkill could become an activated ability, so that Vanish could be saved for more serious situations, and that would allow its power to be strengthened since it would have a cooldown attached instead of being usable every time we entered stealth. The entire Stealth portion of the talent is only a leftover scrap from its original incarnation before being redesigned.
Our cooldown power needs to be cut into pieces but then multiplied in usability. Rogues have always been about controlling the tempo of an encounter, and by providing more interesting choices for us to use, we can truly create a separation between the mindless ganker who clicks all of his CDs in a straight line all at once, and the graceful assassin who weaves their abilities and games their cooldowns to the maximum effect.
Ghostcrawler and the developers have commented several times on their plans to boost our passive survivability and lessen our requirement on uber cooldowns to carry us through difficult situations. I agree with this design, but I'd rather our power came from skillful play instead of a blanket buff that comes at no cost. We should be pushing ourselves to play our best, and we should have an ability toolbox that supports that playstyle. We need more planning ahead, more complex strategies and a more reactive playstyle. I'd like it if playing a rogue felt more like a complicated chess game with skill taking precedence over inexperience, instead of pushing a couple of cooldowns every 3 minutes and then waiting for them to recharge.