I'd argue that for most, living in a suburb is in fact the worst of both worlds. You are neither rural nor city. You have none of the benefits and many of the drawbacks.
For me my decision to live in the city is one of safety (driving cars is dangerous) and time. When I lived in the burbs I spent something like 30-40 full days a year sitting in my car. That's 10% of each year in my car. That's just not a trade I'm willing to make anymore.
My suburban neighborhood growing up did not have sidewalks; not sure if that was unusual. Overall it's my impression that urban areas are much more walkable/bikeable than suburban ones. At the very least, it's difficult to leave or enter individual subdivisions in the suburbs on foot (by design).
Try going to the grocery store in the suburbs on a bike. Sidewalks are great for walking your dog. But in the suburbs, you are trapped to your car.
You can't walk, take the bus, or ride a bike anywhere. Not only because it's 10 miles away, but because there simply is no safe way to get there without a car.
If you're young and reasonably fit, you can pretty much get anywhere. But most people would never consider riding on high speed roads or where there isn't a bike lane.
Sidewalks have been a feature of every city center neighborhood I've lived in (and I've lived in many). Cities can be safer in that I rarely drive and there are visible and predictable pedestrian street crossing everywhere. While pedestrians do get run over, it's at a far less frequent rate than car-on-car accidents happen.
For me my decision to live in the city is one of safety (driving cars is dangerous) and time. When I lived in the burbs I spent something like 30-40 full days a year sitting in my car. That's 10% of each year in my car. That's just not a trade I'm willing to make anymore.