Now that I think about it, if Neji did add something to the curse seal that would make it
equally strong as SST, it would be a bit unfair for the SST users.
Why? It is hinted (or said) that SST enhanced is stronger than CS2 but is harder to obtain.
Think: Of all the SST users so far, only Kboogi, who has a lot of turns, was able to get it so far.
On the other hand, a lot of people was able to obtain CS2 when it came out (Okay, so I'm not sure about this)
So it is only right that SST enhanced is stronger than CS2.
My point: If we added a third level for CS2 that makes it equally or almost as strong as SST enhanced, CS2 will be better to use
Think: Person 1- obtained cs. Person 2- obtained SST
Person 1- got CS2 Person 2-got a few inks
Person 1- got enhanced CS2 Person 2- got seven star enhanced.
Although the two are equally strong in the end, the CS user was able to benefit more since he was able to use the power of cs2 while the other only has the power of SST.
**This is only how I see things...