I suspect that cutting the google deal short was intentionally done leave Google flat footed with no map app on iOS. Simply put it cuts google out of that market for a while leaving Apple the only major player on their device.
While it isn't perfect being the only big map player in that system means that over time customers will just accept that is their only option, and those with problems will see improvements. By the time Google releases a map app many customers may already be committed to the default experience.
Some folks may continue to make comparisons between the two and switch back, but the majority may not and thus an easy win for Apple where if there were a competing Google Maps they would face a far steeper challenge even with time to improve their own product.
As for partnering with MS I think Apple simply wanted to go on their own considering that they were already were severing a partnership over maps.
While it isn't perfect being the only big map player in that system means that over time customers will just accept that is their only option, and those with problems will see improvements. By the time Google releases a map app many customers may already be committed to the default experience.
Some folks may continue to make comparisons between the two and switch back, but the majority may not and thus an easy win for Apple where if there were a competing Google Maps they would face a far steeper challenge even with time to improve their own product.
As for partnering with MS I think Apple simply wanted to go on their own considering that they were already were severing a partnership over maps.