Earlier quoted context omitted.
Because they were getting a reputation for churning the ports too quickly https://www.youtube.com/watch?v=jyTA33HQZLA&t=19s and then they went all-USBC on the MBP before the ecosystem was ready, got absolutely slammed for it, and went back (on magsafe). 4 times bitten, once shy. I'm sure the cynical money reason played a role too, of course, but nobody else is mentioning the 4 times bitten so I felt obliged.
Seriously. I upgraded my iPad to a USB-C version and discovered I couldn't use my 1st-gen (Lightning) Apple Pencil with it even though it's compatible -- because I first had to buy a special female-female USB-C Lightning dongle just to be able to plug it in to pair it. (Even though I can keep using my Lightning charger to charge it separately from my iPad.) Moving from Lightning to USB-C hasn't been too bad for me si…
The Pencil situation is a disaster. There are at least 3 first party versions plus the 3rd party ones. And when version X + 1 comes out they don’t drop support for version X, they use it in a different product for some stupid reason. Probably because the tooling already exists.
So you can find entire matrices online attempting to explain which iPads support which pencils.
It’s horrible. The Lightning -> USB-C transition is probably one of least objectionable parts of pencil history.