Are them pic related? The f-stops that will change one full stop between each of them??

I mean, if I had the right exposure at iso 100, f/1.4 and 1/100. If I changed to iso 200 at 1/100 I would have to diminish the aperture to f/2 right?

If those are the defaults, why aren't most manufacturers following them?

There are many f/1.2, f/1.8 lenses. You can't easily manually calculate how many stops are there between f/1.8 and f/2.8 or f/1.2 and f/2.