Why the County-class destroyers left service early

Why were the Royal Navy's County-class destroyers relatively short-lived?

They became outdated quickly and carried major design compromises around the bulky Sea Slug system.

The forward guns were reliable, but the after missile system dominated the ship. Its launcher, magazine and handling arrangements consumed extensive internal and deck space. Those compromises were difficult to modernize away as air warfare changed. A ship designed around one early guided-weapon system can age faster than its hull.