> And OpenWRT abandoned this goal.
They have not. Individual devices get too old to be supported, but there are plenty of 16 MB devices they still support. Its true that basically every device now has 32MB or more of flash, but there are still plenty out there that don't.
> with a built-in planned obsolescence (what if the new update requires just a bit more space for "calibration data"?). Got it.
The calibration data is from the factory to tune the wifi radios, it doesn't change since its specific to that individual device. I really hate to reply like this on HN, but you don't seem to know what you're talking about. The kinds of constraints you deal with in embedded networking are different than that in general computing. There's a reason systemd wasn't used, and there's a reason OpenWRT devs went through the trouble of developing their own init system. Just because you can't fathom those reasons doesn't mean they don't exist.