i don't think a machine like the 6600 is designed around any expectation that we'll be carting them to classes. it's a heavy duty machine, so it's ... heavy.
the cover isn't "cheapo". i'm quite sure it will last for many years. i much prefer it to the hard cover that came with another one of my machines. because it's soft, i can fold it and set it aside when i'm using the machine. the hard case takes up a lot of precious space.
when you shop for a rolling cart, make sure to measure the machine in all directions and look for a cart that will provide enough inside space for it to fit.