Before the iPhone, traditional cell phones already had smaller headphone jacks: a 2.5mm one was pretty standard. One of the innovative things the iPhone did was replace the smaller port with a standard 3.5mm jack, which allowed people to use regular (potentially high-quality) 3.5mm headphones with it, rather than a crappy 2.5mm headset. The decision eliminated pointless proprietary-ness to integrate with a more vibrant ecosystem.
Job's decision on the iMac to embrace USB and drop the Mac's proprietary ports could be seen in a similar light.
I wish those kinds of decisions were the ones present-day Apple decided to cargo-cult.