I do not agree with you that Arvo Part has not composed music for films. He has done it for Zvyagintsev's "Banishment" (2007) and scores of films made in Estonia and northern Europe. In fact, IMDB lists 63 short and feature films where he was the composer—not including the films that have used his published musical…

Philip Glass' music in recent films and those of Arvo Part used in movies are comparable to Morricone's magnificent scores. May be he has not heard those amazing soundtracks.