Damn this topic is entertaining !
No seriously, why do people try to build good looking ships ? Well it's been told maybe a hundred times here, but i'll just add a layer of it ...
Because building a good looking ship is satisfying, challenging, rewarding, when you manage to build something original, special, it makes you feel different, you feel like you've built something never done before ( well that's not valid for people who reproduce already existing ships, but that's not the topic obviously ) and this feeling is very satifying, while optimizing is at the moment not bringing in any of those. In fact the only thing it is giving is the feeling of having what .... good stats ? Nice fire power ? Well yeah, it's pretty cool, never gonna deny it ! But in the current status of the game, any player who's got at least a couple of neurons could just be like "monkey see, monkey do" the optimizations because they're just not complex enough to be satisfying to be hardly working on. I mean, no one's gonna say "Oh look at this ship, what an awesome optimization, it must have been so hard working on it" while it's just ugly af. At the opposite, someone who's gonna make an awesome looking ship but with poor optimization, people are gonna be like "yeah, you could have done that better, but whatever it's still viable" and still get rewarded and recognized for it's awesome look or interiors.
That's just how it works right now ...
The day optimization will be something may more harder and technical to work on, well this day, it's gonna be as valued as design.