Older doctors will tell you that your kid will have urinary tract infections, or that a little redness at the tip (which is totally normal) is a sign of an infection, or they'll try to retract it and when it doesn't retract (because the foreskin doesn't detach for a couple of years, or even up until puberty for some kids) they'll try to tell you the kid has phimosis and needs to be cut. Aside from medical scare tactics, they'll tell you it's hard to keep clean (but keeping an open wound clean in a diaper is easy?), that they'll be made fun of, that girls won't like it, etc.

None of these things are true, except maybe being made fun of if you're in the south where circumcision rates are still > 50%. But cutting 10,000+ nerve endings off of your kids penis because of maybe some minor future taunting (that's easy to come up with comebacks, like "I'm sorry your parents hate you so much they cut your dick off") isn't really a sane decision.

Source: Also a circumcised father of two boys whose penises have been left intact. Had one bad pediatrician try to scare us into getting our first circumcised when we were in the office because of nothing penis-related (kid was jaundiced, cleared up on its own, but new parents are excitable so we went to the doc), and a minor misunderstanding with our otherwise good current pediatrician almost had our second scheduled to be cut. I shut that down real damn quick.