As for gold-diggers, getting back on topic, I don't see why anyone can object on moral grounds. It is merely a career choice; you make an old man happy by giving him something he can take great pleasure from, not just through sex, but just through company. Sure, the women is going to be the female equivalent of a "yes-man," but by the time you are old isn't this something you would want anyway? And whether or not women like it, having a pretty lady by ones side gives men a sort of "bragging rights" amongst other men; I'm not saying it is right to objectify women in this manner, but it happens nevertheless.
I'd also wager a bet that 75% of the people who oppose being a gold-digger on moral grounds do so at least partly because they don't think they are good looking enough to do it themselves.