Why would you want to order the write of every 128 kB chunk of your MP3 album with regard to every other? A rotating HDD also has a latency of around 10 ms, and you certainly can write an album's worth of MP3 files faster than in 10 seconds - unless you insist on flushing every 128 kB chunk to the medium separately for no apparent reason, of course.
That you need multiple serialized writes for a commit is a valid point, but I would think that for most applications even a write transaction latency of 100 ms isn't a problem. Also, if you overwrite contents of an existing file without changing its size, you don't need any FS journaling at all, as the FS only needs to maintain metadata consistency, it's not a file-content transaction layer (details depend on the FS, obviously).
Cheap SD cards aren't slow because they have a 10 ms write latency, but because they have a very low IOP rate, which you also could not change by adding a cache and a buffer capacitor, but only by parallelizing writes to flash cells.
That you need multiple serialized writes for a commit is a valid point, but I would think that for most applications even a write transaction latency of 100 ms isn't a problem. Also, if you overwrite contents of an existing file without changing its size, you don't need any FS journaling at all, as the FS only needs to maintain metadata consistency, it's not a file-content transaction layer (details depend on the FS, obviously).
Cheap SD cards aren't slow because they have a 10 ms write latency, but because they have a very low IOP rate, which you also could not change by adding a cache and a buffer capacitor, but only by parallelizing writes to flash cells.