Happy New Year,
I've been watching and enjoying the Ken Burns doc series on Jazz. Lots of folks carp about omissions and biases in this and his Country music series, but overall it's a pretty good overview and with lots of context. Jazz, like any musical genre, was shaped by external forces- race, wars, technology, economics, laws- it both reflected and was molded by all of that.
Quite a few great artists at various points expanded their pallets to include orchestral and symphonic arrangements. Usually they didn't aspire to the 60+ members of a traditional symphonic orchestra- but the reach as far as color, timbre and scope were all there. Some of these were very popular. Some jazz fans disdained these recordings as being impure, sometimes precisely because they ended up being popular.
I cannot judge. But it is true the room for improvisation is more limited in these pieces, but other qualities come to the fore- sonic worlds on a par with anything classical composers were doing.