E.g. people know that their values will probably change as they age, and many (though definitely not all) people just kind of shrug their shoulders about this.

Why is this a problem? I don't see any particular reason to want to bind the future-you in 50 years time with your current values. Things change, values change as well, that's normal. Me, for example, I don't feel any particular compunction to make sure my values either do change or do not change in my future (as long as I'm not being coerced, of course).