I don't know how "sensible" the change is, other than you're not going to automatically be treated like a criminal. It is a step in the right direction only due to the latter. If we treated other things (alcohol, for instance) the way that Uruguay is treating cannabis, I think there would be outrage. A national registry of drinkers? Limits on the amounts that one can purchase? That's some heavy-handed bureaucracy at work, and shows that just because something is legal, doesn't mean that it is free-as-in-freedom.
I think you're right about the outrage that would follow a registry of drinkers. However, the degree of outrage something causes is not decided only by how sensible or not it is.
We tend to compare new developments with the status quo. "Sensible" is not used here as an absolute, but to congratulate a step in the right direction.
