because bang's 6A is speed up, and bang's 5B is kinda trashy, most bang players will be using 5A 6A and 5A 2B as blockstrings, which would frame trap the 2A.
it was pretty useful in CS, because if bang used 5A 2B as a blockstring in CS1, he would have to jump cancel or go into 2C.... and 6A was too slow to serve as a frame trap off 5A
in CS2, bang can go 2B 5B now, so they are more likely to use 5A 2B in CS2
i'll think of stuff thats annoying for bang when i get back from school
there is a gap between 2A and 5B now, so you could occasionally get away with 2D after bang's 2A