It is easy to explain, yet you can't understand it without me telling it to you...
Well Minecraft: From the start you have the resources to build medieval builds, which is the main goal in this game, but you can mix other "non building" blocks to make textures of completely different times.. Homewer, the entire minecraft is working on system of building and getting resources, and if you play on Singleplayer then there is no point of making deadly weapons..
On the other hand Starmade: From the start you are motivated to make something powerful and deadly, which will defeat the pirates... The aesthetics don't involve much right ? You are never motivaed to do the most beatufil ship on the world.. you are ment to do the most powerful thing in the space... the whole starmade works on system of fighting and mining resources.
You seem to forget the abundance of hostile creatures in minecraft. Granted, they are not that powerful and are easy to avoid, but if you were not supposed to fight them, they would not be there.
You also forget the point of a sandbox. the
entire point of the game is to build whatever you want. Your logic of aesthetics not being an important part of the game is also hilariously flawed. If the game were as you say, then the trailers would show doomcubes. Pirates would be doomcubes. Shops would be a small block of metal with a shop module in it. Abandoned stations would be big cubes of hull. Asteroids would just be blocks with some ore in them. Because who needs things to look good right?
Instead, the devs set up contests for stations and pirate ships, and chose the best looking of the bunch. Were they the most combat effective of all of them? I doubt it. But they looked really cool.
And even just recently, they updated the asteroid generation
to make them look better.
If the point of the game is to build doomcubes/wedges/whatever, then why would the devs have gone through so much trouble to make the game world look better?
Lets take a look at textures as well. The original textures were trash (sorry Schema!). So they updated them, and have continued to update them. A ship performs the same regardless of what it looks like, so why bother right?
Who needs different colors of hull? They all work the same don't they?
Why can we color weapons? It doesn't affect their performance. For that matter, who needs lights anyway? decoration is pointless, and interiors are just a waste of space, right?
Most of the content in the game is there for the sole porpose of letting players build things that look good.
At this point,
all you seem to be doing is trying to justify building ugly ships, which is simply not something you need to do. You feel free to build ugly ships all you want, but don't go and tell everyone else that they are just wasting time by making things that look good.