Part of the fun in this game is figuring out how to use the tech you have in new ways. By designing your own systems and tailoring what you reasearch you can get very different weapon systems using the same basic tech. With engines for example you do not need to stay with the default strength/expolosion chance. There is a line of tech reasearch that will allow you to raise/lower the chances, and affect the overall power of your engines. Do you want to have engines that are 20% stronger, but use fuel 40% faster and have 3 times the chance to explode when they are hit? It might make the difference between being faster or slower than your oponents, so it might be worth it? That is just one example of the kind of choices available here.
Brian