Originally Posted by
ST Dog
The AoA disagree indicator was supposed to be standard and was incorrectly linked to the AoA indicator option. Due to be corrected in a planned update to the software, but not considered serious enough to warrant an immediate patch.
A bit more digging reveals that it's a little more complicated than that. The AOA DISAGREE annunciation worked as intended on the aircraft of operators who had opted for the PFD AoA indicator (a notable example being American Airlines), but was non-functional on aircraft without that option (i.e. most other airlines' aircraft).
But, as discussed above, one could argue that rather than adding value it was simply a smoke-and-mirrors tactic on the part of Boeing.