I'm going to assume that you are referring to Omaha Beach with this question as Omaha is the usually the focus of these types of questions. The answer is that it wasn't entirely intentional. Assaulting US forces at Omaha were always going to face German machine guns, you can't escape that when amphibiously assaulting a prepared position. At Omaha however a number of things went wrong. First and foremost was the almost complete failure of the naval and aerial bombardment of the defences. This left the majority of German defences intact and ready to face the incoming US assault. The second was the rough seas, these caused havoc with the assault craft and amphibious tanks, many of which were lost in the channel. Smoke and strong currents led many of the assault craft to land their troops in the wrong place leading to confusion on the beach and often further out then expected. In some places, assaulting infantry were landed on sandbars some 100 metres away from the beach. This forced them to wade (and when I say wade it wasn't just the water they had to contend with but also the weight of the gear they carried which even out of the water severely restricted their movement speed) to the beach, all the time under fire from German machine guns, rifle fire, mortars and artillery.

Ultimately, the German defences were not enough to prevent US forces from reaching the shingle on the beach where they found some semblance of cover. Further landings suffered similar losses as the first but gradually more and more troops made it to relative safety and from there officers could plan their next move. The navy played a pivotal role at this point with destroyers closing on the beach and opening up on German defences, one destroyer, the Frankford turned parallel to the beach and opened fire then reversed back along the beach, continuing to provide artillery support. The main objective of the first wave had been the natural draws that would have provided a means for US troops to move inland. These proved to be too heavily defended after the failure of the pre-bombardment. Instead, US troops focused on the bluffs, the spaces between the draws which were more lightly defended. Successfully scaling the bluffs allowed US troops to finally get off the beach and start clearing German defences.

Currently at work so I can't post my sources but I'll edit this as soon as I get home.