And by 3d loops being scripted I mean having a path that recenters him so it doesn't make you go off track but it dependent on your speed. Generations already does this but they make their loops so huge that you need dash pads to go through, thus having no actual control over it since the speed is given to you. We need to have spline paths for 2.5d and 3d to help sonic stay on track, One for 3d being a mixture of a guide path that let you loosely move around so you can track on track where the developer wanted you to go. And another that forces you on that path but you have to have your speed still. Basically keep pushing in a direction to move and he'll keep moving.
Since some of us don't know differences between scripted paths and scripted events. Besides Sonic team uses dash pads through 3d loops so much its a norm.