I completely agree with this! I think contacting potential PIs bumped me up from being an average candidate to a stand-out candidate. I was accepted to all the universities that I had made contact with professors prior to applying, even schools that were definitely long-shots for me. The game plan should not just be to email professors. I established contact with PIs through email, and then set up meetings in person whenever possible (for example, if the universities were near my college or hometown). For universities that were not close by, I made sure to have a phone conversation at the very least. Of course I cannot say with absolute certainty that meeting with professors is what got me in to graduate school, and there are always candidates that are so stellar they don't need to do this, but I don't think it could ever hurt! Contacting professors shows responsibility and enthusiasm.