Cycling with luggage is a very specific type of holiday, often uncomfortable, cold and wet. Or you spend the day covered in sweat, desperate for a shower. It has its merits (I've cycled from France to Switzerland) but having to do it every time I wanted to visit a rural youth hostel would put me right off. It just makes visiting places such as Skye expensive and difficult. Your whole holiday is spent working out timetables and checking you're going to be at the bus stop or whatever in time.
Otherwise without a car you're kind of stuck in the same place. At least in Britain. I used to live in The Netherlands and you don't really need a car there at all. But its still nice to have one, and to able to jump in a car and visit the Veluwe for the day without depending on busses or whatever. And the train network is more extensive in most other countries than in Britain. You would find it almost impossible to visit most castles in rural Aberdeenshire by relying on public transport. Ditto much of the north west Highlands of Scotland.
But I somehow get the feeling that the man in the OP isn't even the sort to have the gumption to visit places like that under his own steam. There are rather a lot of single men on OLD who just do absolutely nothing and stay in their own little world with no desire to explore the rest of it, by car or by public transport. I'd have no problem with one who was really adventurous, but again, I'd wonder why he simply didn't learn to drive to give an additional option of hiring a car.
DdraigGoch So what in life am I actually missing out on without a car? It's harder work but there's not really anything which I've missed as a result. Conversely I'm very fit and have a knack for solving problems rather than panicking and taking the lazy way out*
Believe me, you aren't the only person who is fit and not lazy, and its not an attribute reserved to non-drivers. I didn't learn to drive until I was 27, and you would not believe how hard it was to get myself to races (I run competitively). It involved a lot of cadging lifts, paying for taxis, arriving the night before and staying in a b&b, and its just far cheaper and less time consuming to have a car. And I think the buses run less often now and a few of the places I went, it would no longer be possible to get to.
I remember doing one evening 5k, finishing 3rd, being really pleased and having no damned clue how I was going to get home, as there was a bus to get me there but not back as it was after the last bus at 6pm or something. I had to cadge a lift from a total stranger. (I had hoped there would be someone there I knew). It was so embarrassing.