I wasn't excited to watch it, because I don't find McFarlane funny (as a writer/showrunner and especially not as an actor), and because I think I've only ever enjoyed maybe one sci-fi parody ever. (2 if you count MST3K as "sci-fi"..?)
But my wife wanted to give it a shot because she's such a sci-fi nerd (even more than me), and you're right: they captured the utter essence of Star Trek so completely that I'm not entirely sure why he's not on a short list to do a serious Star Trek show/movie.
The qualities that make Star Trek so compelling (especially Next Generation and to a lesser extent DS9 and Voyager) are ever present in The Orville in spades. That it somehow manages to combine a very serious look at life in space with some pretty raunchy potty humor is nothing short of incredible.
I would fully support McFarlane (or whomever is responsible for that "essence" in Orville) doing a dramatic space opera, hands down, no question. That would be one hell of a show.
Not sure the market would bear it, unfortunately, though.