What's the big deal?

Is trackstanding a critical skill? No.
Is it completely worthless? No.

It's definitely a neat trick, but that doesn't make it important. I personally prefer not to have to unclip at intersections, so I'll slow to an absolute crawl and inch along while waiting for the light to change. I personally can't do a "true" trackstand (staying in one position indefinitely), I have to inch forward.

It's not a huge deal but it is easier (if I keep my butt on the seat, it's uncomfortable to reach a foot down to the ground. And I'm lazy and prefer not to dismount/remount all the time).

If you're trying on a freewheel bike, it helps to have it in a higher gear, and "fight" the brakes. It's easier to balance when there's more resistance to the pedals.