SugarMousePink it's interesting, isn't it? Someone way back on this thread said that they had no problem with lesbians as parents which has I must say, been my experience by and large. But this is predicated on a very restricted notion of parenting as a largely female domain - and much of the scaremongering around gay men as sole carers for a child relates to the fact that they are men. A lot of social conservatives would stress the father's role (in most jurisdictions this has until recently been based on issues of legitimacy and the transfer of property) although the law focuses (again, conservatively) on the proven relationship between mother and child - this often means that fathers are treated very unfairly. Again, it elevates the bodily above other aspects of parenting
I think that a lot of these issues at the social level are about power, and women are often reluctant to cede the one area in which they hold power. My DP and I did decide to take the risk of having an involved donor (like Lenin says, the fear is always about losing custody which is why people prefer to steer clear of involvement) because we didn't want her to build up a fantasy picture in her head (e.g. that she will know that her dad is slightly round, going to go bald, and sometimes short-tempered...) and because provided that we can maintain our good relationship with him, this can only benefit her. He's also (in a reversal of the EJ/DF situation) a lot younger than us, which means that DD will (I assume) have a surviving parent long after we are gone. This means a lot to me, in particular, as my father died when I was 8 (which perhaps also explains my reluctance to take the anonymous route)
I'm rambling, but I do think that historically speaking fathers have been fairly dispensible in terms of upbringing (with the wider social/kinship networks that Lenin was talking about being important). I think good, consistent parental relationships are key, and the way that they are constituted probably doesn't matter hugely. Roles are socially determined, in my view, once you get beyond the very early months.