Think the problem is that there is just so much money you can make on DTV movies nowadays, when everyone and their mothers can and will just pirate them.
In order to increase the production values they would probably have to make them theatrical, and if that ever happens the risk of them also having to 'dumb them down' for non-comic book fans feels way to high for it to be worth it.
Spider-verse with an Oscar push and an Oscar win, made less than 400 million WW. Or less than Far from Home opening weekend.
LEGO Batman made just over 300 million or about 60 million less than Spider-verse. Which even for its sins... half of what Justice League made.