Why? Because it would cost a lot of political capital to address, results would take time to filter through, and your political rivals can hit you hard with populist nonsense in the mean time which will weaken your position electorally. Any intelligent person who values their own re-election is probably not going to risk implementing such a policy, even if all other considerations aside they thought it was for the best.

Perhaps I've been reading too much HP:MoR (not to mention Liar Game), but this strikes me as being a co-ordination problem. That is, nobody can come out in favor of a smart-but-vulnerable policy first, but if everybody could first agree to be in favor if -- and only if -- everyone else agreed, then something could (perhaps) be done.

Now if only there were some sort of Dark Mark we could use... ;-)