Given that they are composed and arranged by some of our most

they are but they're the most commercial type of classical music

"Classical" or "art music" means academic music
It's music that is discussed by professional historians and art critics
It's not just because something is written in orchestral format or uses "classical instruments" that it's classical

>>74679211
Movie scores are film music. They are a specialized type of music, drawing from many types of music, from classical to popular to traditional.

Contemporary classical is the classical music if our age - music written specifically for the concert hall.

Behold the more well-known new classical works written in the last 2 years:
https://en.wikipedia.org/wiki/2016_in_classical_music#New_works
https://en.wikipedia.org/wiki/2017_in_classical_music#New_works

There are many, many more that didn't make these lists.