I would in fact put composers like John Williams and Danny Elfman in their ranks.
For John Williams to be ranked among other classical composers
I'd judge his musicianship by his concert composition. Williams
dedicated his violin concerto to his 1st wife Barbara. It sounds
nothing like his film music. I don't know if Elfman ever wrote
for concert performance.
He is certainly a supremely gifted composer considering
he didn't have the formal training in classical music of Williams.
Yet he could turn out orchestral pieces as moving as 'Black Beauty'.