The US is a maritime nation. We need access to the seas to trade with the rest of the world and to defend our allies. So we need to build warships. If you want something state of the art that can keep up with evolving technology it is going to cost.
As important as it is to have these advanced systems it's even more important to have the ability to produce them. To do that you need a specialized workforce. A warship is not built the same way as a cruise ship. If we don't keep our warship builders employed, they will go out of business and their workforce get dispersed. To give up that capability, then try to reconstitute it would cost a lot more money.