Do you have to Design Ships?

You will probably need to do at least some, but you don't have to get deeply into it to get the game-play benefits of it. Your ships gain nothing for visual style, so a cool-looking ship and one that looks like a junkyard gone horribly wrong will perform the same, assuming they have the same functional modules. Most of the ships I design take 2 or 3 minutes, other people might spend hours building simply because they want their ships to look nice.

Ship design basically consists of researching various functional modules (engines, weapons, defenses, life support, etc), then sticking these onto a hull. There are quite a few non-functional parts available to use to make your ships look nice, but they are entirely optional. Where the funtional bits are placed on the hull is irrelevant.

In the second expansion, there is even an automated feature that will do this for you. You pick how you want the ship set up (for example 50% of space used for weapons, 30% defenses, 20% engines), and the game will make the ship for you. It will even update the design when you research better modules (which I find quite annoying, but that's just me).

also, you can select a template type(es. a medium ship) and just add the funcional parts(engines, weapons,...) to get decent-looking ships without the hassle of designing it, while keeping direct control over what you get on gameplay level.