Infertility means you've got some sort of disease or injury or malformity that makes you unable to have childen through normal intercourse, and it should be addressed by the medical profession with the ethical goal of curing the disease, healing the injury, repairing whatever is getting in the way of naural fertile sex.
Surrogacy does not cure infertility: Mr. and Mrs. Romney are still apparently inable to have children through normal intercourse.The morally upright thing to do, is to seek medical help to cure their infertility. There are effective drugs, devices, and surgery which can often address that problem, and restore their healthy sexual function.
Nobody's against actual CURATIVE medical inervention.
What's wrong is going outside your marriage to impregnate another woman.
Um, yeah- surrogacy DOES cure infertility! An infertile couple now has two beautiful children! God bless them.