I'm fairly certain naked companions and the occasional lack of lip-syncing are genuine bugs (and unintended). Having my helm/mask removed however appears to be intentional, as it's consistent (for the "romance" sequences, my companion's helm is also removed). My guess is someone at BW decided it was important to see your avatar's facial expressions during these sequences. While I appreciate their concern, I'd still rather have the ultimate authority over my character's appearance.