Like it or not interrupts are good for the game, mechanics that are skill based is what is used to separate players. Yes Resto Shamans are obviously the best healer but the way to nerf them is to nerf their healing strength most likely by nerfing the modifiers they get on their heals from Focused Insight / Unleash Elements. Their heals without those up aren't insane but it's the fact that while silenced / locked out they can use Unleash Elements and then have Focused Insight for a massive heal that basically instantly tops them coming out of a lock down. If they get one cast with those buffs up against caster / dps / healer teams they're safe generally and that's the biggest issue - Shamans can get completely smashed by cleave teams but that's more to do with the imbalance of some of those setups than it is to do with Shaman not being strong at healing through it.
In my opinion nerfing things like Grounding CD, and Spell Reflect CD is really the wrong way to go about nerfing survivability and class strength simply because if used very well the abilities are awesome such as when you Ground a Poly or Spell Reflect a Cyclone. On the other hand when used poorly (as most people do to be honest) they really have very little impact at all on the outcome of the game such as all the Warriors who have Spell Reflect just macroed into their D stance and get nothing with it or Shaman who drop Grounding with their other 4 totems every time and ground a Corruption or w/e. A Shaman who is really excellent at shocking is extremely annoying to play against and it makes them and their teammates immeasurably harder to kill and there are plenty who can do it while they're not under pressure, but even at extremely high ratings there are only a handful who really shock well while under pressure and being focused and they really stand out from the pack.
It's really a similar idea with other classes, but the real issue comes when they don't have to land their interrupts in order to get kills etc. That's why I think that Interrupts and other skill based type abilities should always be the last thing to get nerfed but instead they should be focusing on reducing other strengths that the classes have in order to make proper use of those abilities a requirement instead of simply a bonus. Shaman should be required to be great at shocking in order to be successful at high ratings instead of simply being able to sit back and heal through all the damage otherwise why would you ever choose a Paladin over a Shaman? The same issue arises with DKs in my opinion where many top DKs simply have almost completely stopped using Mind Freeze because they know that they don't need it to get a kill at all, but if they do land one then it's almost guaranteed so many DKs will just sit on the interrupt while training your healer and instead rely on things like the Ghoul Charge interrupt, Strangulate, and Ghoul stun in order to stop heals and force the healer into a situation where they have no choice but to heal or die due to high damage and the threat of Necrotic Strike stacking up to unhealable levels.
Anyway, the TL;DR is that classes with strong interrupt mechanics shouldn't have those mechanics nerfed, they should instead be balanced around the assumption that they're landing them and using them well to get kills. IE. Shamans have weaker healing than a pure healer such as a Paladin because they have less utility, and DKs have less damage than other melee because of the strength of Necrotic Strike & their interrupt Mechanics.
I think one of the underlying problems with the game is Wind Shear, specifically it's low CD in conjunction with grounding totem.
With the current state of Shamans, you tend to see them almost every other game. If they're good at shocking then they can severely limit any class that relies on hard casting. This is one of the primary reason why specs like Elemental are non existent among other things.
I've been playing Arcane for the past 4 years, it can pump out retarded damage when left unchecked in BGs, however, in Arenas, it's not uncommon for a Frost Mage to out damage me since i'm left with juking to maybe get one aBlast off then rely on barrage / IL shatters.
Obviously if they tweaked the interrupt system, depending on what degree, they'd possibly have to nerf some of the hard casting abilities such as Frostbolt and especially Arcane Blast. That brings up another problem since it would affect their PvE side. Perhaps it's time just to have two different sets of values on even more abilities like they did with Warrior's Smash.
Basically, Blizzard's on a slippery slope. There's underlying problems with the game with the interrupt system promoting and benefiting classes / specs that have instant abilities while punishing those who hard cast. So they end up over buffing abilities like Frostbolt / Arcane Blast when they should fix the real problem, too strong of instant abilities and short interrupt CDs.
Edit, section added from page 2.
One solution would be to adjust the frequency of lockouts.
-Wind Shear now has a 24 sec CD, upon successfully locking out a target you gain a 10% healing buff for 8 seconds.
-Melee interrupts are now on a 15 second CD.
-Counterspell / Spell lock now are on a 45 second CD.
-Silence (Shadow) is now on a 1 minute CD but can no longer be dispelled.
With the changed interrupts the damage would need to be adjusted on a lot of abilities.
-Ice Lance is now on a 3 second CD.
-The stacking effect of Arcane Blast is no longer effective on Hostile Players.
That's a few changes to the Mage class i could think of if the interrupts were changed as above. Can anyone think of some stuff to their own classes / specs that could be addressed if interrupts changed.
Everyone knows there are problems, many of whom agree that the abundance of classes/specs with interrupts is getting absurd. Vileroze was trying to explain to me a few months back why mages had been pigeon holed into spamming instants, and the aforementioned issue was pmuch what it boiled down to. I don't think wind shear is the problem, I think it's every single class being able to interrupt the fuck out of you all day.