Would your son consider circumcision to be an "improvement"?
From my standpoint, most sons don't care if they're told the truth by their parents at the appropriate ages and not subjected to continuous banter of inequality from those who are uncut.
What's wrong with letting the boy decide?
Nothing if that's the path adults would rather let happen.
What do dads have to lose by letting the lad grow up and then make the decision?
Some families don't have dads in the picture for whatever reason. Mine died when I was 6 so I didn't have him around, but I did have my mom and she did her part to make me feel content about myself, my appearance and understand the fact that despite my differences from some other people that there's absolutely nothing wrong with me.
Since this is a decision that parents shouldn't even have to consider
Your opinion and not a fact...
(most parents in the world would be mystified if told they had to decide on this surgery for their infant)
Not true. My niece had two baby boys, both were circumcised by the decision of herself and her doctor. One is currently 8 and the other is 3. Both are happy, healthy and are not a bit psychologically damaged by the fact that they don't have foreskin. And as long as we keep them away from such overzealous purists who would dare tell them otherwise, they will grow up to be perfectly OK individuals
Ummmmm.... pot, kettle black?
For most, it's not even a question of generosity but what they think is best.
Let the boy decide when he reaches adulthood.
If that's what you want to do with your children, then by all means. If another parent doesn't think that route then so be it. Just refrain from spreading this hateful nonsense about people being abnormal for doing it because
obsessing over maintaining a foreskin is just as crazy.