ActiveX was an alternative to javascript or Java applets, which was an absolute security disaster. Just 10,000 ways for people to install malware no matter how much they tried to patch it. Even once Microsoft realized it was an absolute shitshow that shouldn't exist, they had a hard time getting rid of it, because corporate users kept complaining - they just loved making all their internal tools in ActiveX for some reason.

Unlike some of these, this is a technical disaster rather than an ethical one. Except in the sense that, ethically, you should be good enough at your job that you don't design bridges that collapse.