Other than easy access to nature, all of those points are true for major metro areas. But other than say, Salt Lake City, does any other metro area offer such close access to nature? Boston and Seattle are even much farther away...
I am a pretty avid nature enthusiast that spends a lot of time in the outdoors. It isn't even close, whether you are looking for mountains, water, or parks. Seattle's reputation in this regard is well-deserved; I'm not sure if there is another metro of its size that is so embedded in and connected to nature. And if you look at map, it is easy to see why -- the city is essentially surrounded by water that is surrounded by very rugged mountains (which has provided challenges for growth).
FWIW, the other large metros in the Pacific Northwest (definitely Vancouver and to a lesser extent Portland) have similarly exceptional access to nature. Some of the Mountain West cities also have great access to nature, though not as diverse as Seattle.
Camelback Mountain is half an hour from the center of Phoenix. Virginia Key Beach Park's walking trails are 20 minutes from downtown Miami. Lionel Hampton-Beecher Hills Park is about the same distance from Atlanta. You get the idea.
SF certainly has really nice nature close by, but it's not like other US cities are industrial wastelands.
I'll grant you the Santa Cruz Mountains if you're on the southern end of the Bay. You've also got the hills in the East Bay and various options in Marin and points north if you're in Marin.
But Boston, in addition to various coastal walks has a bunch of nearby parks and small mountains/hills to the west and in southern NH. Also tons of sea kayaking/canoeing. Depending upon where you live, bigger peaks in NH are maybe 2-3 hours.The Sierras are further than that from the SFBA.
Don't get me wrong. The Bay Area has great recreational options but so do a lot of other cities depending upon what you're looking for.
I grew up in suburban Boston. It was a very nice town - we lived on an acre of land, with woods behind the house. Drive 30 minutes in any direction, and you got basically - woods. Maybe some ponds and fields, with scattered houses and suburban town centers between. The city (a pretty nice one) was 30 minutes away. You could get to waterfront, in Boston or Salem or Nahant, but there aren't really beaches in most of Massachusetts (outside of Cape Cod). It did have a massive amount of history, though - in that 30 minute drive was basically everywhere significant to the birth of the USA.
I'm on the peninsula now, in the hills. 10 minute walk to a suburban downtown. 3 minute drive (or ~20 minute walk) and we're on some Bay trails. 5 minute drive and we're in the mountains. 5 minute drive to a massive lake over the San Andreas. 20 minute drive and we're on the beach at the Pacific Ocean. 30 minute drive (or 40 minute Caltrain) and we're up in SF. 30 minute drive and we're in downtown San Jose.
Define "easy access to nature." Where I live, there's a major state park within the city limits and a very large lake within ~20 minutes drive. In ~2 hours I can be at the beach. In ~3-4 hours I can be in the mountains. And untold amounts of basically empty land just outside the city. If you're going to arbitrarily define "easy access to nature" as "mountains next to ocean right next to me", well OK, not a lot of places fit that bill. But that's a very narrow definition designed to fit basically SV.
I can go see thousands of migratory birds a few miles from my apartment. Half Moon Bay is 30-45 minutes away, depending on road conditions. Fairly strenuous hiking and rock-climbing in the Santa Cruz Mountains is also 30-60 minutes away. Santa Cruz itself is not much farther.
I have lived all over the east coast for most of my life, and this degree of access has made an outdoors person of my notoriously sedentary self.
So can I, as I mentioned there's a major state park within the city limits where I live...
> It means I can see a beautiful view without planning a day trip.
Incredibly vague and subjective. What constitutes a "beautiful view"?
> I can meet with groups of friends of all fitness levels and enjoy a pleasant afternoon outdoors where we all have fun.
Not unique to the SF Bay Area at all.
Again I think this is very much a cherry-picked definition of "easy access to nature" that is designed to preclude any place not named "SF Bay Area." Still, the kinds of things you were describing can be found in metro areas all over the country.