Slate posts an interesting answer from Paul Frick, “former infantry staff sergeant, U.S. Marine Corps; three combat tours, three years as an embassy guard and detachment commander:”  

“The most important difference between 1944 and today would be in the realm of guided munitions. I once heard that a single F-15 packs as much firepower as an entire squadron of World War II–era bombers when you take into account explosive weight and the percentage of ordnance you can get on target. (Keep in mind, the F-15 is a fighter/bomber, not a dedicated bomber. If we start talking about the B-52, things get even crazier.) Additionally, naval gun fire support has come a long way since the 1940s. U.S. destroyers and cruisers now only come equipped with one or two 5-inch main guns. In the 1940s, 5-inch guns were almost considered an afterthought. With improved fuses and nearly automatic rates of fire that can be achieved with today’s weapons, you wouldn’t need the hours and hours of shelling they used during World War II landings.”  

“As far as the landings go, with today’s amphibious landing tactics and equipment, you wouldn’t need to land at Omaha Beach at all.”