People like them because some of them are iconic. They are fashion pieces that have outlasted the trends and influenced new generations. It has stayed relevant by releasing classics under new color ways and materials for the new generation.
On top of that, they usually have some of the best if not the best shoe tech available. Nike has introduced materials and tech in the Jordans before any other shoe which has made them a legit basketball sneaker from a functionality perspective.
The fad has cooled down tremendously since I was collecting. But still, some of the shoes are iconic.
When Jordan became a signature shoe it was the pinnacle of what shoe to wear for basketball players. Although it didn't quite reach collection status it was the shoe to be seen in playing. Then And 1 came out and changed the game. Shoes all of a sudden reached to urban cultures. People who weren't ballin started getting into basketball shoes. Before the culture shock the Jordan 11's were the start of it all. But it didn't turn into a collecting frenzy until the Space Jams launched in 2000. It overtook And 1 and created a culture of shoe collectors. Nike saw this phenomenon and started a retro frenzy. It became the pinnacle of sneakers all together. Jordan collecting had it's own subculture which still holds true until today.
Although now Adidas has overrun that subculture. Collecting has now become more of a stock market. J's will always be J's though just like a Ferrari will always be a Ferrari.