You are correct, something is wrong. It was the nerf from gawd during 1.2. I was Lightning spec Sorcerer until a month ago when I changed over to hybrid (20/21 - Lightning/Madness). It is a crying shame that one has to do this to put up any DPS numbers that account for anything, especially in PvP. PvE it is still passible but you still have issues of casting times to get off Thundering Blast, or trying to use Lightning Strike while hoping Chain Lightning procs up so you can fire that off instantly. The damage ability for Lightning is the worst spec for Sorcerer doing DPS. Right now, I run hybrid in both PvE & PvP; no need to change up until such time BW fixes the problem with the Lightning tree.
Also you have to becareful with Chain lighting breaking CC in PVE and PVP. So if you have CC's close to you focus target you have to drop it out or face breaking the cc early (killing the Op or releaseing a full resolved PVP on you).
For Lighting to keep up you pretty much have to be perfect on everything and never miss a cast. (movement fights will kill your DPS numbers). My guild will take my sorc on most runs with us, but most times they rather have my sniper for the dps numbers, and the armor debuff. I am min/max PVE only missing the Mk-4 ear running rakata for the better willpower over the black hole mk-1. But lighting strike hits for 1k in HM FP and crits for 2k best I have seen on my parser. But check AskMrRobot, most of the sorc's if not all putting up high number are madness or hybrid madness since 1.2 nerf.