I find it most helpful against Greeks, where you're inevitably going to wind up in their face at some point. 236B gets punished by them on block, which leads into their very annoying close range poking game, and that's not something you want to just "give" them for free. There's also the fact that a slight misalignment from either a movement input or one of their moves sends you flying past them, which can end in a stab or a launch - not a place you want to be.
Sooner or later you're going to end up point blank with your opponent, where Raphael's long and mid-range game become extremely risky and a less appealing option. Instead of panicking, throwing them out, and hoping for the best, try some of his close range pokes. 3A, 2A, 4K, 6B+K, and 44K are all very important parts of Raphael's close range game, and they all have a certain use for the situation. The face that 6B+K breaks in 14 and is safe is what really seals the deal for me - even on block, you're eating away at their guard gauge and they hardly even know it. 44K is good for this reason as well, and has the added bonus of having excellent TJ frames.
In a nutshell, that's why I like Cantarella Needle.