Interesting thread, and I can see both sides to it, although I'm firmly on the side of considering a car pretty much essential. People have mentioned the fact on here that, of course, a lot of folk are simply not able/allowed to drive because of a medical condition; however, what about people like me who passed their test when young and healthy, who are now disabled - thankfully not in a way that prevents me from driving, but such that 'just a 10-minute walk' will leave me in pain and exhausted for hours?
One thing that doesn't seem to have been addressed here is multi-tasking and doing several errands in one trip. Fair enough if you can walk or get the bus to the supermarket and then get a taxi home with a huge amount of shopping; but what if you want/need to go to several shops or do several errands in one town in one go? Supposing I wanted to go to a local-ish town and, whilst there, buy a bookcase from Argos, get a big trolley-load of shopping from Asda (as it happens, outside the town centre), go to the library to exchange 12 hardbacks, buy a microwave from Currys (different out-of-town retail park), go to the post office and also get a few bits from four or five other shops, I'd plan the most sensible order, get in the car and do all of the errands one by one. how would this be possible using public transport? Even getting a taxi, it would cost you a fortune to pay the driver to go from place to place with you and then wait whilst you did what you needed to in each one. 8 tasks that you could easily do in one day with a car might be perfectly doable without your own car, but they might take you 8 days/separate journeys. Isn't your time far more important than all that?
My parents never had a car when we were kids (Dad was partially sighted and Mum had lessons but got far too nervous to ever continue). Whenever we went on holidays, we had to go on the train, carry our luggage between platforms at every change (often up and down stairs) and constantly watch and be responsible for it all the way. We could never make the most of arrival day by setting off early and having a few hours before check-in time at the accommodation, because we had nowhere to leave our cases. Luggage lockers, where they exist, are all well and good, but you then have to get a taxi back from the town to the railway station again to fetch it. On leaving day, we had to vacate our rooms in the morning and go straight in the taxi to the station, because we had nowhere to leave our luggage. Small B&Bs would have done us a favour and let us leave it for a few hours, but had no room to do so; large hotels had the room for us to do so, but would frequently have 'policies' disallowing it - a security risk both for them (could have been a bomb) and for us (anybody could steal anything). Now, we load up the car on leaving day (sometimes most of it the night before) and there the luggage safely stays, whilst we do whatever we want, until such time as we arrive home and unload it (or leave it until the next morning if we're late back and tired).
The first car we had in the family was a shared one when my DSis and I passed our tests at a similar time (me at 18 and her at 22) - and the immediate sense of liberation and much easier, less stressful lives we all felt - even though we were all fully used to not having a car for years - was immense for all of us.