In IL its required by law, I haven't had a front plate in the last 6 years and haven't gotten a ticket for it (old M Coupe and then my C63). we just got our X3 M Sport last year and I told them no front plate (ruins the M Sport look), I got pulled over about a month ago (going 38 in a 25) cop let me go for some reason but asked where my front plate was, I didn't hesitate and just said our front bumper was just replaced and they didn't have the bracket for it yet... He just said okay and that was it. No ticket for speeding or front plate. I am sure he has heard that before though. probably a good idea to keep your plate in the trunk if he asks to see it or something like that. Really depends on where you live, I see TONS of cars by me with no front plate, usually either old beaters where they fell off or newer sport cars (hardly ever see a corvette with front plates).
to me if I ever get a ticket, its worth the $70 or whatever, as long as I don't get several in a single year (or by the same cop, that would be a nightmare if they were on your way to work working the same route every day!) Also this probably varies from State to State but I think its a secondary offense type thing, where they can't pull you over just for that. So if you aren't speeding he can't pull you over for not having a front plate... not 100% sure on that though.