It appears that Apple has begun quietly phasing out its trailer download options from thetrailers.apple.com website, effectively eliminating 1080p trailer availability.
Previously, the site gave users the ability to stream trailers in 480p or 720p, along with providing download options for 480p, 720p, and 1080p. Trailers uploaded to the site after an approximate date of May 22 no longer have any download options and can only be streamed in-browser at 480p or 720p.
I have confirmed this as well. It is slightly annoying because I used to download the big 1080p trailers that I especially liked and save them or watch them again later and things like that. I do suspect I was in the minority though so I guess I shouldn’t be surprised.