There's a time and place for everything
Now, let me be perfectly clear: I'm not saying you should ALWAYS eat pizza with a knife and fork. If you're eating a single slice, using a knife and fork is just silly, and asking the guy behind the counter for some cutlery is a good way to get banned for life. Likewise, if you're at a party and someone orders pizza, you should go with the crowd and handle that slice with your bare mitts.
If, however, you're at a restaurant with a few other people, and you've ordered a whole pie that arrives at the table on a metal tray, hot and fresh from a brick oven imported from the old country, you owe it to yourself to try using the knife and fork that were there when you sat down.
Sure, you might get some awkward looks from your fellow diners, but you'll be too busy appreciating the hell out of your pizza on a whole new level to care. You'll finish the meal with a renewed purpose, and a desire to change the world -- or, you'll say, "that was stupid" and never eat pizza with a fork again. Either way, you'll have eaten the best food in the world, so what does it matter?