I asked that same question here a year a couple years ago, and instead of "I don't know" answers, I got answers that didn't make sense at all.
I then asked it in a different way, like.....Why don't they make a AA rechargable battery that has 1.5 volts like other batteries, and got the same ridiculous answers, so I just gave it up.
Anyway, the 1,25 don't last near as long in voltage sensive devices. Like you said, 1,2 is considered dead in many cases. So I quit using them, as they are not worth the hassle. If you buy large quantities of AA alkalines, at like HD, you are way ahead,