The fact that it allowed for all kinds of topologies, and that it served as a bus (shared medium, hence the name 'Ether') rather than a point-to-point link is what I think made the biggest difference.

Of course now that we all use switched links they are point-to-point again but an ethernet 'hub' gave you the same effect as a bus with all devices seeing all of the traffic. This made efficient broadcast protocols possible and also allowed for a historical - but interesting - trick: the screw-on taps that you could place on a single coaxial cable running down a department giving instant access without pulling another cable. Zero network configuration required, just get the tap in place and assign a new address. DHCP later took care of that need as well.

This was fraught with problems, for instance a single transceiver going haywire could make a whole segment unusable and good luck finding the culprit. But compared to the competition it absolutely rocked.