In terms of gross salary, absolutely. In terms of net earnings after paying for the cost of living in London, probably not. I'm quite sure I could double or even triple my salary by moving to London, but my quality of life would very likely go down. For a start, where I live I can afford to buy a house. On a multiple of my income in London I don't think I could do that.
I see no value in earning more just to pass the money directly to my landlord.
Remember that your savings are measured in absolute terms. If outside London I'd earn x and spend 25% of it on housing and in London I earn 2x and spend 50% of it on housing, I'm still earning more non-housing money in London. And in the case of paying a mortgage then at the end of it all you sell the house, so the extra expenditure isn't "lost".
Quality of life comes down to personal preference. I'm not sure there's anywhere else I could live (at least without having to learn another language) and not feel any need to own or use a car, the pub theatre scene is probably the best in the world (likewise the museum collections), a huge range of musical performances, and it's the best place to find people for specialised hobbies (netrunner in my case, again literally the best place in the world for it in terms of the community size). Of course other places have their own selling points, but London has a lot going for it if you like that sort of thing.
I lived in London for 12 years, and earned good money working in banking. I loved it for all the reasons you spelled out. But then the financial crisis happened, the banks started firing people, we got burgled three times in one year, and I got mugged at knifepoint. We moved out to the countryside where our kids could go to good state schools and found that they stopped having asthma attacks. I earn less money, but I'm much less stressed.
It's worth saying that despite what one hears in the media, both burglary and knife crime are continuously falling.
But sure. I think age, kids and general lifestyle make a lot of difference; for a lot of people London delivers more of what you want when you're young, but the countryside is better as you grow older and your priorities change.
A lot of devs in London are here to amass as much money as they can, so that they can retire early or at least move to a cheaper location later in life. While doing so, they are fine with living in substandard conditions (such as flatsharing in their thirties).
I see no value in earning more just to pass the money directly to my landlord.