Tracks provide far superior off-road capabilities. It's not that the design just 'stuck around', there were even attempts to make tanks that had wheels which would fold down for road useage and fold back up to go off road, just those were very clunky and hard to keep operable. The main thing is, tanks spent the majority of combat time off road, so they need the much, much higher grip, and much lower footprint weight, than wheels can ever give. Indeed, that was the whole point of the halftrack design- to create something in-between which would be better for off-road and could take some of the weight of armour, without losing too much speed. Armoured cars meanwhile stuck with tires as they were meant to be traveling extremely fast up and down roads, and didn't need much off-road performance due to low weight.