You are correct in that all foreskins are different. I read that 5% of men do not have full coverage by the time they reach adulthood.
There are pros and cons to circumcision. I grew up in the time of naked shower after phys ed class and got made fun of since I was the only one who was not circumcised that I knew of until I was 17.
At the time I would have done almost anything to be normal. If that were still the case these days I would advocate doing whatever the social custom is. But since boys today will probably never be in a situation where they have to be naked in front of other kids, and circumcision rates have dramatically dropped in the last 20 years, I don't think it is as much a concern.