The problem with making SCs strong enough to warrant using them any time other than Self SC or SC of Opportunity (which I love, but are fairly rare. These are SCs where right as you get TP, someone uses a WS that you can SC with, so you wait half a second before you WS so as to not get that "to soon" SCmiss, and then you can more than double your WS damage), is that it would make samurai even more fucking overpowered than it already is. As it stands, sam is so @^$#%ing easy to play and do stupid amounts of damage that it makes people who put significant amounts of work into other DD jobs effectively less useful than an army of brain-dead AH samurais who have no idea how to gear their job and just hoard str gear. Add in an intelligent sam, and the difference is even more staggering. The amount of work it takes for the few jobs that can come close to rivaling an equally geared sam is outrageous (basically, ukonwar with amazing gear vs amano/masa sam can go either way, but that depends entirely on the players, and the sam will still have the advantage. Any other job is pretty much SOL.)

The reason people have forgotten about how powerful sam is is abyssea, where anyone with a crit WS pretty much wins the game. SE has made it VERY clear they have absolutely no intention of continuing to make abyssea-like content, and once you step foot outside of abyssea, it becomes very clear, very quickly, how overpowered sam still is. Every other job has basically gotten neat toys between 75 and 99, while sam got Broken-ittai (Konzen-ittai) which basically takes sam's insane damage potential and makes it even more ridiculous.

Basically, keep in mind that good sams were able to keep up, and compete with, other DDs inside abyssea, WITHOUT HAVING A CRIT WS. The don't lose nearly as much from the lack of the 50~60% increase to crit damage and rate outside of abyssea.

tl;dr: You can't buff SCs unless you nerf Sam.