This is what passes for +5 insightful these days?
The issue isn't opening an email: but clicking a link in that email or, worse, clicking a link that takes you to a legitimate looking site and entering data, or opening an attachment in a legitimate looking email.
There are all sorts of attack vectors present from an email message. To sweep it all up as "IT's Problem" is a very, very bad idea. It just takes one email fooling the right person to be a security problem.
PhishMe's philosophy is that at some point the technical protection will fail ... so you'd better ensure that your employees know what to look for. The best way to teach them what to look for is to let them actually experience safe emails using the same techniques that would be maliciously used against them.
Spear-phishing isn't an idle threat, it's a widely used attack method that has gotten data out of targets like the New York Times, Defense Department, Facebook, and Apple (http://www.theatlanticwire.com/technology/2013/02/spear-phishing-security-advice/62304/). I'm sure that each of those companies has a very robust and capable IT Department armed with email scanning and sanitizing software. You just can't catch everything with technology.