> Improvement in production processes and materials (e.g. magnetic coatings) allowing smaller tracks

Improvements in coatings improve the data per track, but no improvement was needed for increasing the amount of tracks. On a 1.44MB drive there are 100 000 bits per track, but only 80 tracks per side. Or, in other terms, the length of a single bit along the track (on the innermost track) was ~1.2µm, and the width of that same bit, sideways to the track, was ~200µm, for an aspect ratio of 166:1. As far as the media was concerned, roughly 10:1 aspect ratio would have been more than enough, or a normal 1.44MB floppy could have supported more than a 1000 tracks per side.

The limiting factor was that old floppies had no way for the head to follow the track, it was just indexed into a fixed position by the drive mechanism. This meant that the tracks had to be ridiculously wide to support all the possible misalignment on both the reader and the writer. To improve track density, what was needed was some mechanism to make the head locate the tracks and follow them as the disk rotated under them. Iomega solved this by etching shallow concentric circles for the tracks on the surface of the disc. These rings were essentially invisible for the magnetic head, but allowed a separate laser to pick the up and follow them.