Other than aquilo there is no reason other than aesthetics to put it down. You'll get exoskeleton before you can make enough concrete to make a difference.

It depends on how you play I guess. I'm constantly running on foot short distances where it doesnt make sense to look for a car. Lots of doubling over your factory running spaghetti lines and expanding out existing sites a few tiles at a time.

Late game you can hangout in the map and place things remotely but thats not how it usually is for me. Also keep in mind a game can last many dozens of hours so all speed boost add up over time. I believe concrete also synergizes with the exoskeleton legs and vehicles.

So moderate convinence and aesthetics I guess. A little speed goes a long way. However its too much of a chore to place it by hand any meaningful area needing to be filled is thousands of tiles usually. So its best to wait until you can have the robots do it for you.

Just because it's a tiny increase and you're not always walking doesn't mean it doesn't add up to a lot when you play for like 200 hours