war is basically two dudes fighting over something
you've got the 'fighting' part down but the 'something' is lacking
the entire point of a beach raid is to drive the defenders back far enough for the attackers to get a foothold and stay there
the point of shooting dudes on the way up to the foothold is so that you can get up to the foothold without being shot at by the dudes that are defending the foothold, thus allowing you to actually capture the foothold without being knocked back down by the defenders
And just shooting people will give other people who actually want to capture the point an opportunity to capture it.
the problem with this train of logic is that people will always just shoot eachother if it is an option- if you're going to include an objective, the objective has to be the only way to win or else it's just going to waste