Pff, if that annoying and totally ineffective UAC dialog is the best they could do in more than 5 years of development, I shudder to think what happens when increased security is not the goal of a release.
And btw, I don't know what you mean by the early XP era, but you're probably referring to a timespan of at least 20 years.
Yeah, I was being sloppy. There was and is malware on Windows for a long time but it only became a widely recognized "epidemic" in the late 90s - early 2000s.
but the real point is that it's just nonsensical to say that Microsoft has been more focused on security as a reaction to bad press of Vista - whether you like or hate Microsoft or Windows or Vista, there's just no interpretation of the timeline under which that makes any sense.