Users will not understand that TURKTRUST did something wrong. They just see that Chrome is broken. More abstractly, one of the problems of the CA system is, tha

Users will not understand that TURKTRUST did something wrong. They just see that Chrome is broken. More abstractly, one of the problems of the CA system is, that no one has any incentive to do the right thing. CAs will try to hide a breach in the chain of trust, since discovering the coverup is no worse for them than discovering the original breach. And blacklisting a CA in a browser will degrade the user experience, so browser vendors are reluctant to do so.