Dunno about you, but when I was a Kid, shopping centres didnt exist, and we walked to the shops so it wasnt an issue, certainly not in our house, or many friends for that matter.
I bet cars have widened in that time, and car park spaces and now very regimented and often tight so the 'supermarkets' can cram as many as possible into their limited space.
Very handy for the parents initially getting the, very bulky, and heavy baby filled car seats in and out, then as time moves on, space to set the buggy up, and then later I suppose a slightly safer way of introducing road safety. Plus a bit more space to open the door to strech across to strap em in. I certainly view them as helpful for the parents, and for the owners of the car next door.
nearness....I bet its a lot easier for a lone adult / couple to push their trolly, carry their bag across a car park, than it is for a 'family' to push their logically larger shop, and get the kids safely back to the car.
Ideally, make every space a foot wider and do away with them all

but, I think they are a good compromise.
yes, everyone could manage without em...people used to, but hey, why not make life a little easier. The 'ordinary' spaces at our shops start about 2 cars further away in each aisle, not a lot further for anyone to walk in the grand scheme of things