They did the modem because it's actually cheaper for them. They already bought the Intel division and had engineers work on it for over 5 years, so it's already sunk costs at best. Since they came up with a working design, it is FOR SURE cheaper for them to use it than to buy something from Qualcomm.

I'm a bit suspicious about this, because if it was truly great, they would have waited longer to advertise it as a must have feature for their "pro" devices.

It's sort of beta testing the thing on the lower volume product with less tech literate people who won't complain too much because of some weird connectivity issues.

If it performs, Apple is going to make even more money on the next round of iPhone, not that Apple needs any more money but you know, if that could stop them from increasing the price, that could be nice.