iPad and MacBook are converging
It's really just a matter of input preference. Do you want to touch the screen, with the detachable keyboard, or do you want a touchless screen, in which case the keyboard needs to always be there. macOS and iPadOS will continue to evolve until they meet in the middle, unfortunately.
I recently bough the 12.9" iPad Pro. They basically force you to buy the removable keyboard by disabling the split, on-screen keyboard. Why can I use split keyboard on my 9.8-inch iPad Pro, where my thumbs easily reach the middle of the screen, but not on a larger iPad, where reaching the center is a real problem (when holding the iPad upright with the rest of your fingers).