There really is no advantage to bending your cue after the break.
It does really increase the chance that you will snap your cue or shaft at or near the joint!
I think it comes as a result from an accentuated follow through, which is a good thing on the break, but only if it's in the right direction.
The best break tip I have ever heard originally came from Charlie "Hillbilly" Bryant. Basically, he said that you should follow through and try to keep your tip from touching the table. What this does is keeps you flat through the cueball, which helps keep the cueball from jumping before it hits the stack. This is huge!
I think that when great players ,as have been shown in this thread, are bending the cue it is a result of the follow through and happens long after the tip hits the cueball. But when most players try to replicate that break, they hit down on the cue ball and their break suffers. The cueball fly's around and jumps in the air too much.
I know that I break much better when I keep it flat and level.