Your system has to be reliable, especially at sea. The ship has to react like you expect. Over time, requirements for electric systems and ships change. Changing notions require more and other devices in wheelhouse and engine room. The installation matures from infant to adult. The easy solution is to place new equipment where there is -at that moment- room for it, but is that also the best solution?
Read how the electric system on the Banjaard matured (dutch).