The airlines could help themselves by offering the emergency exit seats to tall people at checkin or embarkment. It would avoid a lot of aggravation for the cabin crew. I'm too tall to sit straight in standard seats, and so have to sit with my legs sideways, jutting into the personal space of my neighbours (who justifiably complain), or out into the aisle where they interfere with cabin crew.
Not going to happen on check-in because it's a problem when doing it online. Airlines do allow you to check-in online, and then go to the c/s desk (or at bag drop) to request the e/e row seat. They tend to check you out then to see whether you are potentially capable of operating the emergency exit, because that's the only reason why you should be sitting there.
Airlines used to make available ALL their seating on seating charts (and BA still does for the over-wing exits), but then on embarkment and final check found that too many unsuitable people were sat in emergency exit seating (minors, babies, elderly), so emergency exit seating on long-haul flights tends to be bookable only at the airport (and on some airlines, on paying the appropriate surcharge).
S.