How a few legitimate app developers threaten the entire Android userbase (Ars Technica)

Rootability would be great but would solve nothing connected with this problem. Only a vanishingly tiny fraction of owners are mentally equipped to use such a feature, and only vanishingly tiny fraction of phones have any alternative firmware available to put on them, anyway. Those alternatives have their own security problems and update-channel problems.

Accountability could be helpful if it could be made to work, but the legal "industry" has very mature and sophisticated tools at hand to sidestep such obligations.

Solutions that don't actually work can be worse than no apparent solution at all.

A system of required source-code escrow and insurance deposits, with a separate agency to roll out automatic updates for affected hardware, could be made to work. I doubt anything short of that could. (Likewise for home routers.)