In very specific situations (in the summer on a sunny day in a low-crime area when its just you commuting with no small children or excessive cargo and no time pressure) walking a few blocks to and from a train station could indeed be a pleasant experience. Take away a few of those points though and cars start to look pretty attractive again. Even more so if we're talking about a hypothetical self-driving future where several of the few remaining disadvantages of cars have been mitigated.