Absolutely nothing!
Has anybody ever gotten a reply from a web form? Ever? What the hell is the point of these things other than to distance yourself from somebody who is trying to reach you?
I rely on email for a fair bit of what I do during the run of a day, and I need to get replys in order to to my job properly. If a companys contact info uses proper email, I have something I can track and follow up on. If a company uses web forms, there is zero accountability. Sure, I get a generated page that says my message was successfully sent, but who the hell knows?
This is not to say that I always get a reply when I use REAL email, but it more of an exception when I don't. With webforms, I may get a reply to one out of every twenty sent.