A lot of commercial software such as Windows and Photoshop do this, and it must have been approved by legal. So I suppose this is currently considered the best way to do it.
A range like 2002-2020 conveys two ideas: that the work has been around for a while, and that it is still maintained. Both are important for corporate folks who want an assurance of stability.
Of course, it’s probably just automated, since updating the copyright with changes once a year is probably too big of a pain.