You're welcome to design solely for an audience that has hover support, just as you're welcome to design solely for an audience that has IE installed.
Perhaps you should also put up a popup: "This site best experienced with a computer that has a mouse. If you are visiting with a phone or touch-screen tablet, please consider buying a computer, or visiting one of our many fine competitors."
Remember when lots of websites had messages urging you to visit with specific browsers? Remember how much fun that was?
I don't think that's unreasonable if you're reasonably sure your audience is close to entirely IE.
When I make websites I have no time for ideals or philosophical statements, I look for where my market is now and where it's going in the short term, and make my decisions based on that.
I've seen many applications that were created under that assumption ("they're 'intranet' apps, and IE is our corporate browser") only to become extranet applications quite suddenly - undermining that assumption by merely replacing "in" with "ex" in the functional spec.
It's not just a philosophical statement. It's a practical matter. Unless your plan is to high-tail it out of there and leave it to someone else to maintain your mess, that is.
The difference between philosophical statements and practical matters is surprisingly difficult to articulate. You can rarely point to a single moment when the one becomes the other.
Every practical situation starts out life as a philosophical position. The atomic bomb was once a napkin doodle.
Where would accessibility fit into all of this? Ideally we should all be designing sites in a way that doesn't rely on hover, to make our sites accessible to the blind and disabled.
Edit: Isn't the problem with touchscreens ultimately "focus", and not "hover"? There's no way to select an element without activating it at the same time.
I think this is just a matter of designing for your audience, not a matter of "moving forward".