In Folland's Quantum Field Theory he mentions that we can apply Feynman's formula (Feynman parameterization) to either the Wick rotated integrals or the non-Wick rotated integrals corresponding to Feynman diagrams. However, later in the section he outlines a regularization procedure, in which he says we must first Wick rotating the integrals. Why is this Wick rotation necessary? Is it to make use of certain properties of Euclidean space that are not shared by Minkowski space? If so, which ones?