feel free to disagree
I do, shanks.
Overall you have to bear in mind that the poem was written in 1919. Society was different then. Though I won't hide behind that fact overmuch.

Would he have wished these on his son? Not to be good-looking, because invaribaly (well really?) good looking people turn out to be dimbulbs?
He's wishing her not to be too good-looking, ("not/Beauty to make a stranger's eye distraught"), because that can mean attention for the wrong reasons, and that the good-looking person has less need to cultivate himself/herself. Such people may even lose "The heart-revealing intimacy/That chooses right" by associating themselves overmuch with their appearance. Are you sure this kind of thing doesn't still happen? I'm sure many film stars would say it does.

Would he want him not to have opinions - because invariably (well really?) opinions lead to hatred?
Well, Yeats is talking about opinions in the sense of "being opinionated" here, I think. Opinionated people (of whatever gender) can be entertaining in the short term, but become wearisome in the long term. Definitely a barrier to social success, even if you spend a lot of time in the company of intellectuals.
Oh, and don't take social success as meaning solely taking the official tried and trusted line. Anarchists socialise too!

I've already said that Yeats' wish for his daughter not to have any hatred is idealistic. But on the other hand, it's common parental practice to wish children a life free of pain, fear and loss, however impossible that may be.

Would he want him to be taken in by a gentle, decorous family?
Yeats emphasizes the importance of "custom" and "ceremony", which you could say are lacking in many families these days. Old family structures have broken down, and the new structures are only just starting to take shape. For sure, we'll be OK eventually, but there are a lot of rudderless ships out there at the moment. If you've spent a little time in a rudderless ship, you'll realise that it's not a good thing, and not something you'd wish on any of your children.

To some extent I'm just playing Devil's Advocate, as I don't think the poem is that wonderful. However, I think your reaction against it is more extreme than is justified by the poem itself.

I am, of course, talking as a parent myself, which may be just a little significant.