To whom? How many people who have bought these things ever heard of OpenWRT? How many of those are capable of installing it?
Have you ever considered upgrading your refrigerator? Washing machine? Kettle? A router is a transparent appliance to most people.
And that's why we educate others and let them know about their options. You have to start somewhere.
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The point is somewhat less that you will do it, as being able to do it implies a certain level of sanity to what you're buying + the ability to use the hardware even if the software goes away in some undefined-yet-predictable fashion.
It's sorta like checking if spare parts are available for your refrigerator or washing machine.