I don’t like that idea because it makes something that should be a one-button press into a lot more inputs, and I’m not a fan of using currency to buy currency as a general principle. It masks the value of what you’re buying, and it tends to make you overpay.
I’ve made a suggestion here that would keep CXP to unlock discounts on parts, but parts are bought with credits directly, and use CP for something that actually makes sense.