Not only Maimonides, but everyone in non-circumcising cultures from Philo of Alexandria to J H Kellogg knew that the foreskin gives pleasure. This is forgotten only where men don't have them.
I recognsie the studies you mention.
The first (Laumann) only found the difference in old men; did not correct for ethnicity; relied on self-report of circumcision status; and later, using the same data found "...circumcision generally do[es] not result in increased odds of experiencing sexual dysfunction."
The second (Krieger, Bailey, Moses et al.) was based on paid adult volunteers for circumcision, conducted by circumcision advocates. There was a striking decrease in sexual dysfunction in both circumcised and control groups, indicating something else was going on.
The third (Williamson and Williamson) was based on 145 Iowa mothers (only 54% of those who were asked) of whom only 24 had experience of both, and at least one (who had had a daughter) was not invited to take part until she had said she would have circumcised a son. In other words, it was rigged.
For the rest,
http://yourlogicalfallacyis.com/slippery-slopeSo Angela Merkel doesn't want Germany to be the only country where babies (boys and girls) are protected from having (the best) part of their genitals cut off? She should hold hands with Sweden, the Netherlands and Finland (and why not the whole EU?), and all do it together.
