Yes, it is simple to use Nagle's algorithm in some cases, however, it will degrade server performance if not being used wisely, we do not want to open another can of worm here. Thank you for the suggestion any way. :-)
It is trivial for us to implement the "nph" feature as every thing required is there already.
I agree with you that "nph" hack is not a good thing, instead, we can easily add a configuration entry to control the buffered/unbuffered behavior for any request, but it is not bad idea to has an Apache compatible mode.