Maybe it's not because of SATA 6Gbps but because random read and QD=1 did not improve since Intel X25-M/E?
20MB/s is what we could get on Intel's and it's what we get on SF drives and C300...
QD32 of >200MB/s is nice (and useful for me), but not ever used by an average user.

You're looking at the wrong culprit