AFAIK statistics need to be added to each and every driver and
AFAIK MikroTik takes those drivers directly from Linux Kernel without modification.
I do not think this feature request will go trough for 2 reasons:
a) there are too many drivers out there - so too much work
b) By modifying drivers MT will cut possibility to update drivers in easy way when there are changes in Linux Kernel drivers
Right thing to do is to bother manufacturers of original Linux Kernel drivers to add those features, and then just ask MT to update those new drivers from Kernel.