From what I know about manufacturing...
More work put into a piece of track = more room for error. Part of the reason RMC coasters are so smooth is because such a large percentage of the work is done by CNC equipment and the only work done by humans is welding it together. So many more welds have to be done to accomodate ties, rails, track connectors, the like. This is just like ~10 welds per piece of track and while they are longer, it's more consistent than welding points of ties in spots along the spine. There's a little over half the room for them to fudge the manufacturing in these track pieces as there is on an I-box coaster with two rails that require a little less work than this one does. Not to mention it's easier to work with this one rail in a shop than it is something bigger, as it's small enough to fit through a regulation doorway as opposed to a huge piece of B&M or Intamin track.
Fun fact: Jeff Pike said that the way metal behaves when welded is actually the reason behind the long straightaway around Steel Force's turn, instead of accounting for it in the design Morgan just kind of let it do its thing and then added that to fill it in.