Navy's futuristic weapons a target for budget cuts
In a perfect and peaceful planet, we wouldn't need such new weaponry technology, but we do not live in such utopia and we do need to keep strategic and tactical advantages over our enemies, current and in the future.
With the global economy, China is being funded to become an important military power in not so far future, look at them trying to replicate our current stealth plane's technology and this declared development of a carrier-killer missiles we can't just wait.
Besides, these developments always produce side technologies with lots of civil utilization. Would we have give up the space race and not landed in the Moon, we wouldn't be probably using the electronic components we have now that makes possible cellphones and lots of other wonders.
If it is not for the sake of protecting ourselves in the future, we need those technologies for when we get out and start exploring our solar system. Such class of weapons would be used as shields for deflecting high speed objects against our future ships.
