My guess for this is that the average user doesn't parse text on pages as fast as more tech-savvy users. That delay is perfectly timed for the average user to grab their attention.
For me, I use google so often that I can rapidly parse information without really needing to read much of the text, the link just sort of 'looks' right. I've observed my wife reading google results and she is much slower and more methodical, probably because she doesn't google things 20+ times a day every day like I do.
That's how I end up misclicking, because i'm not working at the speed of a normal googler.
It is really annoying though, there are some css tweaks you can make using browser extensions to make that disappear if you're so inclined.