Why were the teachings of Aristotle so accepted by the church in the middle ages?

I'm not sure where you get this idea from.

In fact they often weren't accepted, leading to tremendous conflicts within the 12th c Paris cathedral schools (universities) and resulting in excommunications like that of Peter Abelard

It was the subject of further internal rancour and debate in the late 13th c within the scholastics and the Paris Masters, leading to enormous efforts of dialectic (and untold pages of writing) by Thomas Acquinas. It took several hundred years for Acquinas' position and thinking on reconciliation with Aristotelianism to be accepted into Church teachings.