Circumcision prevents phimosis

True, but phimosis isn't common. It's not like "oh, if we don't cut him, he'll most likely get phimosis". Besides, that can be resolved later in life if it actually becomes an issue, and doesn't even necessarily require circumcision to fix, depending on the severity of the phimosis. Is it worth permanently removing part of a body without the person's informed consent because it might cause problems later in life?

Circumcision reduces STDs and UTIs

By such a small amount it's virtually irrelevant. You quote that statistic of "3 times more likely", but 3 times an incredibly small number is still an incredibly small number. Besides, you know what stops that stuff even better? A condom. If you knew your son was going to have a one-night stand with someone, you'd always recommend they use a condom, regardless if they had their foreskin or not. You'd make sure they always knew to be safe. So foreskin is pretty much irrelevant to this.

Women prefer circumcised sexual partners

In America perhaps. Not true around the world. Women tend to prefer the types of penises that they're exposed to (giggity). In a culture where men are circumcised, women prefer circumcised. In a culture when men are not circumcised, women prefer uncircumcised. Surveys of that nature conducted in Europe get different results than one conducted in North America. Besides, when an uncircumcised penis is fully erect, the foreskin retracts on its own and it pretty much indistinguishable from a circumcised penis, especially to a lot of women who aren't as intimately familiar with them as their owners would be.

But in the end, the point I'm trying to make is... is it worth chopping off a part of someone's body permanently because of an incredibly small chance that it might be the source of a problem in the future, even if they aren't old or mature enough to make the decision for themselves? If so, may as well before double mastectomies on all female children in order to stop most breast cancers. May as well remove extraneous fingers like our pinkies since that's technically a small reduction in chance of contracting skin cancer, since you don't have as much skin.

The reasoning of chopping off bits of someone's body without their consent just because they might be problematic in the future is absolutely absurd.