You, as a Roman Catholic, have every right to that view, which is also echoed in some evangelical quarters. The idea to many other sincere Christians is that they are letting married Cousin Jane temporarily put herself in some semblance of the biological position of Aunt Bertha, with the consent of her husband. Good Christians do differ over this. And I do not want to offend anyone’s sincere faith in Christ.
The underlying idea is this: the healthy, normal, human body, complete in every detail: God demonstrates very, very often that that's what He wants for us.
God's design for us at the outset, at Creation, was very good (that was the First Reading at Mass today!). That's why real medicine is legitimate: because legitimate medicine has the aim of restoring the body, as far as possible, to its normal, healthy condition.
Contraception (to impair the body with a drug, device, or surgery, to disable its power and design)) treats the good, fertile, womanly body as if it's got a design defect. Something that's bad. This is an untruth, and rather an aspersion cast upon the Creator, as if to say, "You made me, and all other healthy normal women, wrong, wrong, seriously wrong: but AHA! I'll nullify it."
Fertility isn't a design defect. It's a design feature. And the Designer said so.
So drugs, devices and surgery are OK if they are directed toward restoring, healing, curing, returning the body back to normal function. BUT...
Think of hormonal drugging & surgery to change one's ... er, what do they call it? gender? ... It has a whole lot in common with contraception: using drugs, devices, and surgery to change one's sexuality by making oneself a procreative neuter.
If Cousin Jane "put herself in some semblance of the biological position of" Nephew Gary, it wouldn't conform to any revelation of the Will of God that I know of.
Um... Book of Neuteronomy?
(I'm not trying to offend anyone's sincere faith. Certainly not your, my dear HiTech. I'm just applying the principle to discover the implications.)
(And the priciple, "It's OK to chemically/surgically impair your body to alter or disable your sexuality," is wrong.) I don't see how the practice of medicine can ethically intentionally cause a disorder, rather than cure it. Contraception, like sex-change surgery, causes a disorder, wether it's temporary or permanent. I would have to call that a disordered medical practice.
I would welcome a further discussion, if you want.
Um.
Otherwise, I'm outside to plant more garlic if the weather holds. :o)