When a friend of mine had IVF, she and her DH wanted her to join him in the cubicle and assist him. The clinic staff said no. Porn, however, was provided.
So apparently getting off to a picture of some other woman was more acceptable than your wife helping you out. 
But seriously - if the men would like some additional help (and who wouldn't, under those circumstances), shouldn't it at least be an option for their partner to provide it?