Cutting hair and fingernails doesn't actually hurt; and they grow back.
Not really analogous. Pulling out fingernails, (like declawing cats, which I believe is still legal in some countries), now that would be analogous, but I think most people would draw the line as that.

So far as religious requirements go, well, most religions accumulate stuff that they need to get rid off from time to time, and that kind of reform has to come from inside the communities involved. Can't be pushed on them from outside, and attempts to do that just reinforce resistance to the change.

As I understand it both Jewish and Islamic tradition accepts that where there are serious reasons to avoid circumcision, such as haemophilia, a man can be a full member of these religions without beng ciurcumcised. That means that there is no absolute requirement even within the existing traditions, and that implies that there is room for movement.