[woodson]

I guess that's in part because it's even more difficult to (manually) transcribe speech into articulatory-phonetic elements based on the acoustic signal (laryngeal gestures?? Clearly they are there in articulation, but their acoustic correlates are masked to some extent).

Automatic alignment methods are probably quite hard to implement, given the various coarticulation patterns in the signal depending on context/prosodic position etc.

Could you provide a link to papers or other materials dealing with articulatory features in speech recognition?

I guess I should take another look at Browman/Goldstein's Articulatory Phonology