I don't think it's a total deal breaker and given the size of the ride, it's themed incredibly well with virtually no supports visible.
The thing about Disney being able to hide track so well is that they build three types of coasters:
- One is based around a train (Big Thunder, Seven Dwarfs and Everest) This means for theming, it's always low to ground and has ballast to disguise it. These aren't that intense and supports are almost invisible.
- They build a coaster like California Screamin' which is based on a traditional amusement park coaster from the early amusement parks or Slinky which has exposed track but it's based on a toy kit, either way, exposed steel makes sense and fits the theme. These allow for more freedom and in California Screamin's case, a much more intense experience.
- They hide the coaster in a dark room like RnRC or what I assume Guardians will be like, this allows for the most intense experiences. Everest does this also.
The more intense the ride (Or how fun the coaster is, depending on your view point), the harder it is to theme is the main point here.
Hagrid's coaster is in the sweet spot between theming and fun. Could Universal have done more to theme the track better? Sure but it either will result in a less fun coaster or the cost skyrockets. I also think that this coaster is a response to some people's disappoint in Gringotts being a 'coaster'. I'm not one of these people, I loved Gringotts.
My main concern in all this was to do the pathways but they can be easy enough to theme, roughen or dirty up for a better effect. Unfortunately, they're a necessarily evil (if you can call it that) as they're needed for safety.
Edit: And then there's Tron...