There's a big conceptual difference between providing an indication which is driven from AoA (in whole or part) such as 'eyebrows' or a 'low speed cue', and actually providing an AoA indication itself.
With the former options, it can be pretty accurately determined how these will be used, and they can be presented - or not presented! - in the appropriate circumstances, and even manipulated in some circumstances. (On one of our types the 'eyebrow' feature appears during windshear alerts, but not otherwise, IIRC)
A 'pure' AoA display is far more prone to abuse, and makes the designers far more nervous about its presentation, reliability, veracity. And raises more certification issues, too.