We'll skip the first three ("You have to circumcise the baby so that he will match his dad" and "My first son is circumcised, so I have to circumcise my second son" and "My husband is the one with the penis, so it is his choice"), since as presented they are close to myths.
Myth: Everyone is circumcised. Reality check: Actually, world-wide, only 30% of men are circumcised, and most of these men are Muslim (WHO 2007). Most modern, Westernized countries have rates well below 20%. In the United States about 25 years ago, around 85% of babies were circumcised. The rates have dropped substantially to 32% in 2009, according to a report by the Centers for Disease Control (El Becheraoui 2010).
Here the authors cite a 2010 conference presentation regarding data gathered in a survey that wasn't designed to measure circumcision rates. The New York Times quoted a CDC spokesperson as saying "we cannot comment on the accuracy of this particular estimate of infant male circumcision." Figures that the CDC have actually released are about 55%, but they caution that these underestimate the true rate.
Myth: Circumcision is an important tradition that has been going on forever. Reality check: In the United States, circumcision wasn't popularized until Victorian times, when a few doctors began to recommend it to prevent children from masturbating. Dr. Kellogg (of Corn Flakes fame) advocated circumcision for pubescent boys and girls to stop masturbation...
Ah, this old myth (and the obligatory Kellogg quote, too). No matter how striking it is, it's an error to conclude that circumcision arose because of Kellogg's recommendation. People advocate all kinds of things for all kinds of reasons. People in the late 19th century advocated circumcision for a variety of reasons, too. Gollaher, in his "Circumcision: a history of the world's most controversial surgery" devotes only a handful of pages to masturbation; he traces the history to a Lewis Sayre, who (oddly) believed circumcision could cure certain types of paralysis.
Myth: Circumcision makes sex better for the woman. and Myth: Women don't want to have sex with uncircumcised men. Reality check: In a landmark study of US women, 85% who had experienced both circumcised and intact men preferred sex with intact men.
Here the authors cite a study by O'Hara, which recruited most of the participants from an anti-circumcision mailing list, thus severely biasing the results. Credible studies, without such biases, find the opposite. See, for example, here.
Myth: "Being circumcised doesn't affect my sex life." Reality check: Men who are circumcised are 60% more likely to have difficulty identifying and expressing their feelings, which can cause marital difficulties (Bollinger 2010).
Here the authors cite an unpublished study by the second author.
Circumcised men are 4.5 times more likely to be diagnosed with erectile dysfunction, use drugs like Viagra, and to suffer from premature ejaculation (Bollinger 2010, Tang 2011).
Here the authors engage in cherry-picking. From memory, 3 studies have found increased risk of ED, 3 have found decreased risk, and six have found no statistically significant difference.
Men who were circumcised as adults experienced decreased sensation and decreased quality of erection, and both they and their partners experienced generally less satisfaction with sex (Kim 2007, Solinis 2007).
Again, the authors are engaging in cherry-picking. More studies report increased sensation than report decreased sensation, we've dealt with ED and partner satisfaction above. There is a reasonable summary of the research at Wikipedia.
Myth: "If I were any more sensitive, it would be a problem." Reality check: The foreskin contains several special structures that increase sexual pleasure, including the frenulum and ridged band (the end of the foreskin where it becomes internal), both of which are removed in circumcision. The LEAST sensitive parts of the foreskin are more sensitive than the MOST sensitive parts of the circumcised penis (Sorrells 2007).
Here the authors cite a flawed study by Sorrells et al. The authors arrived at this conclusion by testing their results for statistical significance and ignoring the result (see here). Interestingly, the authors only assessed the ability to sense the lightest touch; they did not test sensitivity to sexual stimulation. Schober et al did (admittedly with a small sample of uncircumcised men), and found that the foreskin is actually the least sexually sensitive part of the penis.
It may feel like the penis is overly sensitive to a circumcised man because there is little sensation left to indicate excitement, leading to unexpected premature ejaculation (a common problem with circumcised young men).
Actually more common among uncircumcised young men.
However, as circumcised penises age they become calloused and much less sensitive. (See the interview listed below for more details.)
Better still, see the peer-reviewed research which shows that the level of "callousing" (keratinisation) is the same in circumcised and uncircumcised men (see here), and that the glans penis is equally sensitive (see here, here, here and here).