Not trying to put words in yer mouth, but I’m not sure you mean ‘random’ so much as -human-.
See this: http://www.steinberg.net/forums/viewtopic.php?f=228&t=86179
It would be nice if one could sample an audio file and create a ‘template’ of the amplitudes that one could apply to MIDI note velocities. OR… copy a ‘curve’ of MIDI velocities from one file to another.
For your drum example. I’ll play MIDI drums and the velocities of the rolls come out far more realistic than I could program without a LOT of ‘randomising’ as you’d like to do. Sometimes I’m too lazy to fire up the kit. I wish I could somehow -store- the velocities of drum patterns; not the actual notes, just the way the velocities alternate and than map them (or ‘paint them’) on top of a drum pattern I draw in manually.
Same thing with strings. I often need to draw in some alternating violin bowing. I have other songs with really good patterns–where the bowing sounds realistic and not like a sewing machine. I wish I could ‘paint’ the velocities from that song pattern onto a new song’s MIDI.
I also use L/E but frankly, it’s often more bother than it’s worth… I haven’t built up a large enough library of ‘presets’. I wish they included more presets of the kind yer asking about.