The 6502 and the 6800 are pretty similar. The 6501 was pin compatible with the 6800, but not software compatible; the 6501 was dropped as part of a settlement with Motorola.

Changing an in-progress system design to a similar chip that was much less expensive ($25 at the convention vs $175 for a 6800, dropped to $69 the month after the convention) is a leap of faith, but the difference in cost is obvious justification, and the Apple I had no legacy to work with.

It would have been great if Windows NT could have picked up utf-8, but it's a bigger leap and the benefit wasn't as clear; variable width code points are painful in a lot of ways, and 16-bits for a code point seemed like it would be enough for anybody.