The main problem with Coaster Track is that it telegraphs in a highly visible way exactly what it is - a Roller Coaster. Such structures are found pretty exclusively in one type of place - Amusement/Theme Parks.
The issue is that when you're in a Theme Park you're generally not meant to feel like you're in a Theme Park, you're meant to feel like you're somewhere else. Generally, both you and the park have paid a lot of money for the illusion that you're somewhere else. High-flying exposed coaster track is the quickest way to undercut all the rest of the immersion and remind people where they actually are instead of where they're meant to feel like they are. Which defeats much of the purpose of a Theme Park vs. a mere Amusement Park.
There are ways of doing it that work; as someone mentioned earlier, Velocicoaster is set Jurassic World, which is still a theme park, so a coaster isn't wholly inappropriate. That sort of level of thematic redundancy isn't my personal favorite, but it's technically a fair justification for exposed coaster track. How the sightlines impact the other lands is a bit of a different story, but your mileage may vary about how much that sort of intrusion bothers you. But within it, the exposed track doesn't break the theme of the land because "Theme Park" is the theme of that land.
However, the places within theme parks where "Theme Park" is the theme are few and far between, precisely because so much of the design goal of a theme park is to help you forget you're actually in one. So a good first step to doing that is to mask out anyting that screams "Theme Park". That's why Disney doesn't have a lot of Ferris Wheels, either - they give away the "secret" that this whole place is actually a kind of Amusement Park, despite millions of dollars and years of construction meant to convince you otherwise.