3D printers should become much faster, and more precise.
Belts are slightly elastic and at high speed with high jerk they will and do stretch momentarily and create small artifacts in the print product.
We can get an extremely fast and precise 3d printer by replacing belt drive with spline drive:
Attachment 13268
The axis gears should be double helical so that there is no vibration from the gears.
The rest of the design is left to the reader
That would make the a lot difference. But it would need setting the motor at a distance and the U-joints would eat up some good energy and that would make a dent in precision.
The drive should be direct (no joints), adjusting the motor position along the axis it belongs to and then making it screw drive as in the Z-axis of Anet A8 would prove to be more precise but at he cost of speed.
Using rack and pinion mechanism is a bit harder but if achieved would be fast and more reliable when it is properly constrained. And that needs good amount of lubrication else there will be lots of wear and tear. Having oil bath would mean oil will get out for sure and will be messy.
So the current belt drive is the best option available to us. Proper tightening of the belt and designing the belts so they stay the way they should is the way to go.