Depends on the kid, and what you have in terms of wagons/multiple strollers, etc.
I used to walk to the bus with a 2.5 year old that was a GOOD listener. So I knew that if I said "wait/stop/don't touch" he would follow direction. I also used to have an almost 3 year old that still strollered it, because he was a runner. I couldn't take a chance on him darting into traffic. He also didn't listen worth a dang...LoL.
I think the backpack thingies are fine. If it keeps a kid safe, who cares what it looks like? They just have a negative (undeserved) representation.