You seem to imply that a city can be either pedestrian-friendly or car-dependent, but there is an intermediate state: pedestrian-and-car-friendly.
Furthermore, pedestrian-friendly is nice if you manage to sleep in a nice accommodation at a walkable distance from your centers of interest: this is usually the case when you visit a town as a tourist, but not so easy when you leave there.
On the walkability and livability of Prague: having lived there for a few decades, I claim that you can't have both: mostly, you'll get a lot of talk for walkability, and a lot of construction for drivability (which has, so far, only brought more traffic into the city). Worst case, you'll get an intermediate state that's pedestrian-and-car-hostile (there are such places right in the city center, where a north-south freeway had been rammed through).
However, for all the roadbuilding of the past 30+ years, the city remains well walkable, in a loose sense: the dense public transit network (a dirt-cheap yearly pass, trains running separate from all other traffic, semi-separated light rail, and an auxillary bus network) allows me to move about easily: walk a bit, hop on, ride a few stops, walk a bit again. This way, anything is within my "walking" distance. So, even though I'm not living in the city center, I can get there within half an hour (or in half an hour by car, hunting for parking spots included).
This, I believe, is the crucial part: walking by itself is okay for short distances, but needs efficient public transport on longer trips: "we'll just buy a bus or two" doesn't cut it.
(So, yes, it's easy even when living here: walking is not a tourist attraction, it's a mode of transport; and I even see a lot of tourists on the metro, "doing as the Romans do": using public transport as an extension of their legs.)
Furthermore, pedestrian-friendly is nice if you manage to sleep in a nice accommodation at a walkable distance from your centers of interest: this is usually the case when you visit a town as a tourist, but not so easy when you leave there.