Replaced them with what? HDMI, which needs an adapter and can't be fed from VGA sources? DP/MiniDP, which again needs an adapter and can't be fed from VGA or HDMI sources? Maybe USB-C, which doesn't need an adapter if you bought an Apple laptop within the last few hours and don't need to put it on charge? (Otherwise it requires an adapter in order to interface with DisplayPort - but hey, at least it has that backwards compatibility!)

VGA's popular because it's the only option that actually works for everyone, and it's not for a lack of newer alternatives - in fact, the plethora of newer alternatives is the problem here.