“Ashkenazim seem more prone to Machloket. ”
Another good reason for that is explained by the Chida.
He says that Ashkenazim are from Binyamin and are tougher people. Hashem put them in Europe because they could withstand the harsh galut of Esav. Binyamin was the only son who did not bow in front of Esav. That maaseh avot was needed for the banim.