I, too, have been troubled by the lack of pre-board announcements on AA (sometimes no pre-board is offered F class, either). When I observe the boarding procedure, it appears this results for two reasons:

1) They are not pre-boarding elites (which results in gratuitous humiliation by the FA in front of other pax if one attempts to board).

2) They are boarding elites (in which case, the only elites who receive the pre-board benefits are those who ignore the instructions in front of other pax. This, too, can result in hostility-- this time from other pax who can see the non-allowed seat number/class of service printed in very large type on the boarding pass and wonder why you're being pushy).

In either case, this lack of consistency is troubling and would seem somewhat easy to cure via proper training.