I think you'll find they're for high revenue/elite passengers on BA too, albeit not officially. I have a very tall colleague who always tries to arrange a seat with legroom whenever he flies BA and has only succeeded on a couple of occasions (and we're talking calling BA a couple of weeks in advance on some occasions).

Personally, I try to get a seat that is a) acceptable to a not very tall me) and b) not likely to get taken off me for operational reasons (the last thing I want is a fight with a bad tempered gate agent).

Regards
I