Because I prefer a set of simple and basic tools used in combination to accomplish something instead of a "push this button and it does everything" approach. It's the *nix pipe mentality of combining simple well built tools to build solid and reliable things that you can adapt any way you please.
I also build things that are heavy on the network side, and virtualization drops networking performance a great deal (this may be changed these days, not sure).
Don't get me wrong. I don't fear virtualization. I use virtualbox and vmware heavily for development, and yes they do have a purpose, but it's a bad fit for the type of projects I build.
I just find that anything in life that just continues to add features for the sake of adding features, and create more and more "magic" push buttons to solve your problems eventually goes to crap and becomes a fragmented dependency hell that I would rather not deal with. And yes, I do love Golang.
What? AWS is great because it has a nice console but it also gives you direct access to all the VMs and there is a AWS command line you can install to program/script everything. What's missing here?
There's no reason to fear virtualization, and the automation is definitely one of the best aspects of running in a major cloud.