Numetal brings the average down for music too, and admittedly some of my favorite movies came out in the 2000s (Oldboy, Mulholland Drive) so this is a hard take to defend, but hear me out.

Spiritually, the 2000s were completely bankrupt in terms of mass media with big backing behind it. Post 9/11 doomerism and the West's immature anti-war sentiment rarely coalesced into anything meaningful in the domain of what big capital could get behind and put into production in a film studio. However, individual artists were flourishing, and Rock was finally dying, Grunge was mostly defeated and Post Rock, Post Punk, would be born in its place, while Hip Hop would begin to become a massive cultural force in the wake of Tupac and Biggie's death, yet before the Drake era (admittedly I think that besides Nas, Outkast, MF DOOM there's not an enormous amount of Hip Hop from this period that withstood the test of time as well as, say, Radiohead and GYBE).

edit: This opinion is too based to be removed for not saying main