The solution of "just giving in" on the part of the LD spouse would seem to be simple at first glance but in reality I believe it is extremely complicated.
If it was that easy, the LD spouse would have figured it out and would just do it and frequency would not be an issue (of course "quality" would be an issue).
I have found that there are so many "demons" that this approach does not fit at all with the LD spouse. I have briefly discussed with my ND spouse who indicates that she believes she should not have to do anything she doesn't want to. This is probably a typical kind of response from many LD'rs. She indicates she feels more like some type of hooker if she accepts performing a "wifely duty". The consistant response I get is "why don't you leave me alone and just mb rather than pester me, after all why do I have to be a receptical for your needs - do it on your own". Not sure if many LDr's give that direct response, but I suspect many are thinking along those lines.
With respect to the HDr, somehow having a partner that is either sound asleep or wishes you would just go away takes a great deal of the edge off of the experience - particularly if it is 3 times a week.
Finally, I seriously doubt that the LD'r would grow to enjoy the experience - I suspect that she(he) would grow to resent you.