My current husband and my son aren't circumsized but my ex husband was and as far as I could tell, it never interfered with his sexual pleasure. We had sex almost daily and he never had any problems with erections or orgasms. I've read a bit on the topic and it's controversial whether it interferes with a man's sexual pleasure.
Let me clarify what I wrote. Males who are uncircumcised may have way more sexual pleasure. Males who are circumcised have sexual pleasure, too, and they have no idea what they are missing because they've never had it. It's like if you only ever had brownies for dessert, then you never tried brownies with ice cream and chocolate syrup with whipped cream on top. The people to listen to about this are males who had gotten circumcised later on in life and therefore know the difference.
This presents a problem for a lot of study designs which rely on asking group A about pleasure and group B about pleasure when they ought to be asking group C to quantify the difference between when they were members of group A vs when they were members of group C. Meta-studies which include the former type of study design will no doubt have some mixed results or inconclusive results because they have added statistical noise. So, for example, this type of study is most appropriate:
There was a decrease in masturbatory pleasure and sexual enjoyment after circumcision, indicating that adult circumcision adversely affects sexual function in many men, possibly because of complications of the surgery and a loss of nerve endings.
pubmed.ncbi.nlm.nih.gov
Note that while I have framed this as always a negative difference, yes, everyone is different and so there is variability. Even so, the group average goes one way. Consider also that this is in modern times with many surgical changes from when this was implemented in ancient times. Death rate and various mistakes would have been much higher than today.
An example of the former type of study would be one like this:
The highest-quality studies suggest that medical male circumcision has no adverse effect on sexual function, sensitivity, sexual sensation, or satisfaction.
pubmed.ncbi.nlm.nih.gov
The 1++, 2++, and 2+ studies uniformly found that circumcision had no overall adverse effect on penile sensitivity, sexual arousal, sexual sensation, erectile function, premature ejaculation, ejaculatory latency, orgasm difficulties, sexual satisfaction, pleasure, or pain during penetration.
First and foremost, it is not an examination of group C when they were in group A versus group B.
Mechanistically, this makes sense. The foreskin contains tens of thousands of fine-touch nerve endings, protects the glans so it remains more sensitive, and provides natural lubrication. Remove the foreskin, and you remove those nerve endings, expose the glans to abrasion (which toughens it), and take away natural lubrication. That affects masturbation most of all--penetration less so, because lubrication is supplied by a partner.
Getting back to the point as I had written "channel people toward procreation," I had written this because this makes up for the natural lubrication of the foreskin. That is, in my opinion penetration is less effected than masturbation or masturbation is way more fun for the uncircumcised. If you want to get them in line to pro-create and enjoy penetration as much or more (than masturbation), they will only get the lubrication (in ancient times) from pro-creation.
I should add that the pattern of sensitivity changes after circumcision. The foreskin and the tip of the glans (especially when covered and protected) are normally the most sensitive regions. After circumcision, the foreskin is gone and much of the glans becomes desensitized through constant exposure, leaving the ventral area near the frenulum as the most sensitive part. That area is primarily stimulated during penetration rather than masturbation. This shift again appears to bias sexual pleasure toward procreation rather than solo stimulation.
The glans of the circumcised penis is less sensitive to fine touch than the glans of the uncircumcised penis. The transitional region from the external to the internal prepuce is the most sensitive region of the uncircumcised penis and more sensitive than the most sensitive region of the...
pubmed.ncbi.nlm.nih.gov
If masturbation became less pleasurable while penetration was relatively unaffected, the cultural incentive would be obvious. In that sense, the function looks uncomfortably similar to female circumcision — reducing solo or “excessive” sexual pleasure in favor of reproduction.