Another reason would be "laziness" of the corporates, there is no real interest in spending lots of time and effort for creating the bottom end parts that may o

Another reason would be "laziness" of the corporates, there is no real interest in spending lots of time and effort for creating the bottom end parts that may or may not improve the overall system and instead the preference is to build the top-level features and let the ssd vendors deal with the flash itself. Especially when the flash properties change between generations and even in the lifetime of the flash itself. Flash generations also come by very quickly as it is already.