May be SSD should add something like "raw mode", when controller just reports everything he knows about disk, and operating system takes in control the disk, so firmware won't cause unexpected pauses. After all, operating system knows more, what files are not likely to be touched, what files are changing often, etc.
The industry is moving toward a mid-point of having the flash translation layer still implemented on the drive so that it can present a normal block device interface, but exposing enough details that the OS can have a better idea of whether garbage collection is urgently needed: http://anandtech.com/show/9720/ocz-announces-first-sata-host...
Moving the FTL entirely onto the CPU throws compatibility out the window; you can no longer access the drive from more than one operating system, and UEFI counts. You'll also need to frequently re-write the FTL to support new flash interfaces.
OS compatibility is important for laptops/desktops, but not in at least some database / server applications, and those are the applications that would benefit most from raw access
And now we must rely on each OS to implement their own version of a virtual firmware, and do comparisons between different implementations, etc. etc. etc.
This has existed for a long time, see the Linux kernel's mtd infrastructure, and the filesystems designed to run on top of it (jffs, yaffs). It used to be used in a lot of embedded devices before eMMC became cheap, and is still used in things like home routers.
I am not sure how well mtd's abstraction fits with modern Flash chips, though.
