Agreed, we need to weigh the potential that multiple independent guns can have on the gameplay versus coupled ones.
Four separate guns can fire at 4 separate targets, is that good or bad?
In a way it's good, the area being suppressed is marginally larger and the suppression can be more efficient with some coordinated timing. On the other hand less of the area around a single target will be affected. Coupled with the terrain that makes coordinates act quirky it also means barrages could become much less accurate and therefore less effective. But once people get the hang of it I believe 4 separate guns would provide more value than coupled ones in this case.
2 guys less on the beach is a good tradeoff if the Allies gain more than they lose in terms of number of moving targets on the actual beach.