Rumours suggest Apple will go back to Magsafe ( hooray ) and offer USB-C as additional functionality. That way the mental model is simple. You want, fast, full speed usage of your Laptop you use the original charger. If you use USB-C to charge, dont expect it to keep you full voltage given it depends on both cables and charger.
I have also wanted USB-C cable to simplify into two model instead of giving 6 options.( if I remember correctly, may be more in the newer 2.1 specification ) Just 2, thinner cable = (may be 30W), and thicker cable is Full USB4 + 240W capability.
Right now you can even have USB-C cable without data lane. Although no longer possible with USB-C spec 2.1, but that doesn't solve the problem as there are no mandatory requirement to force the usage of newer spec.
It really is a bag of hurt. USB should now stands for Universally Silly Branding.