Well, I hope more people are allowed to use them. I made them for one reason and one reason only: People should use them if they have problems creating their own. And believe me, I know how hard it is to get them right.
To me there's nor right or wrong when it comes to the use of prefabs alone. Only....
IF you use prefabs, make sure that your track fits. There's nothing more annoying than a bad track that uses good prefabs. If the transitions are well done and the prefabs FIT in the ride, then IMO there's nothing wrong with using prefabs.
I DO realize that the prefabs I made don't fit right away for most coasters though.
Buster