There are probably economies of scale associated with maintaining nuclear weapons. Whether you have 1500 or 3500, you need a “large scale nukes” program. You’re not going to cut costs in half by cutting nukes in half.

You also have to consider that nukes have to be distributed around the world, so that you can target enemies throughout the world, so that enemies don’t know where to target their missile defense systems, and so that you still have adequate threat if sites are attacked.