Well first off, SI is not OP. Statistically, considering how abundant they are, people are much more likely to perceive them as OP because they are getting killed by them most frequently... not to mention that lightning is the most visible effect on the battlefield and thus will stand out more in someone's mind. The perception that the SI is OP is false though.
With that said... all the people whining and crying on the forums about them is going to end up getting the Consular nerfed as well. They're not going to nerf one class and leave its mirror alone.
As someone who has played a Sorcerer and a Shadow, both extensively in PvP, I can say that neither AC, on either side, needs nerfed. In fact, I think both are perfectly fine as they are... and nerfing either AC will severely imbalance the game.
People don't realize it now, because when they get killed and they see lightning, they want to QQ about how OP the Inquisitor is. People are somehow operating under the perception that the Inquisitor is doing much much much more damage than it really does. Maybe people are only looking at the damage output at the end of the game... but the funny thing is that when I play my Sorcerer, I rarely get focused at all. People generally leave me alone while I sit back and free cast on all the melee going at each other in one big cluster.
Maybe if people stopped attacking the tanks and started focusing on healers/casters a little more, they would realize that they're nothing but food when you play against them the way that you're supposed to.
Skip to 9:00 if you want to see my level 20 Jedi Shadow going 1v1 against a 29 Sorcerer, both of us from full health, and winning with 66% health. Overpowered? Heh. Right....