You don't need that many def cooldowns. I can keep saying this enough... You are more tanky and have greater survivability than tanks and do very high dps. And yes if Mara/sent need three cooldowns to be able to do viable dps because they are squishy... So do sorcs, ops, mercs, and all three trees of vanguard. You cannot have the best survivability and near best dps in the game and call that balanced... Ever. You do get a mez in awe, a channeled stun in stasis, a slow, and a gap closer with an immobilize for free! No talent points needed. More, abilities and improvements on the ones you already have with talents. That is unbalanced.
The counter to argument about sorcs is that they are supposed to be a ranged class and need those extra def cool down abilities to just survive melee to be able to do their damage. Tgat sounds ridiculous right? It's just as ridiculous as a Mara/sent saying it. I have one. I play it some times. Typically I pop my first cooldown continually push one button while I channel surf, after 10 seconds or so I pop the second... Push another button repeatedly, keep flipping channels... If other guy is still alive I hit guarded by the force, push my third button repeatedly and take a sip or three of water. If the guy is still alive and i havent found a channel i likeI med pak and force camo away. Then when I am hydrated and not channel surfing I go smash the war hero geared sorcs sages ops scoundrels mercs commandos in my BM gear... I avoid attacking the other classes because that would require me to pay less attention to my tv shows...
Just to correct you, you need 2/2 in "Stagger" from the carnage tree to have an immobilize effect on force charge. And if you took your time to look at what other classes have to fight maras, instead of looking at what they DON'T HAVE I'm sure you'll find pvp more enjoyable. Just like every competetive game, you have to improve yourself instead of talking down on your opponent. I am sure if you start looking at what you, as an individual can do to fight the marauder staring right at you. He got one slow which is melee and consumes two rage, that's one GCD you will have to use on building rage again (this is from a carnage mara perspective) The same mara will also boast a 1 sec immobilization from force charge due to being carnage. That's one gap closer save stealth.
Just send me a PM of which class ya play, and I'll try to indulge you in some counters to maras. A one liner would be: Just kite the batsh*t out of them.