So a lot of the discution about getting people "out of cars" is not about getting people to never drive, but to get them to not own a car, such that they have to make the concious decision of renting a car for the holidays, if this is the best choice, for instance. What you describe sound like this.
Obviously, this opens the question of how to improve the car rental market to make those options real options. This is where car-sharing systems and the like come in.
If you need a car for a longer trip abroad, you probably need a different kind of car rental, but the advantage is that every time you can tailor the kind of car you rent for the purpose you need it for. Get a station car or minivan for vacation, a tiny electric car for a short trip with no luggage, or a van if you need to move some serious stuff.
If I lived in Boston/Cambridge, say, and rarely needed to leave the city I'd probably be fine with not owning a car. But just 5 minutes ago, I was emailing with some friends about getting together on the weekend somewhere out in the country. Yes, I could rent a Zipcar or a conventional rental but that gets old for doing things out of the city on a regular basis--especially spontaneously.
But there are comments on this thread to the effect of "But I don't really need to go anywhere. I have the Internet." And that's a fundamentally different perspective and set of priorities.
For me a car isn't for getting around the city or getting to work (I much prefer walking/biking/taking public transport for that), but getting away from the city. To get to my favourite walking trail by the sea or the local ski slope is a 30 minute drive or 1.5+ hours by public transport. Getting to the slightly larger ski resort is a 90 minute drive or almost 4 hours by public transport. Getting to a national park I like visiting is a 2.5 hour drive and virtually impossible to get to by public transport. With public transport I can vacation in most major cities in Europe. With a car I can vacation in tiny beautiful out of the way places I never would have even thought of visiting before I got car.