Personally I find the trickiness of using Kontakt to be one of BIAB's biggest shortcomings. Yes, one can drag a midi file into one's DAW and play it through Kontakt there. But that is not the same as being able to use Kontakt easily within BIAB, because often composition and patch choice are mutually dependent. That is, the instrument you are playing through impacts your choice of what to play through it. Having to imagine how a BIAB-generated track will sound through a Kontakt library is a big workflow speed-bump which disrupts the creative cycle. My 2 cents anyway.

I guess Rewire is not an option?