Star Wars is interesting in that there are no “alien” ship designs because EVERYONE is an “alien” in some way or another, even the humans. The ships are more often designed by corporations than by specific races.

This sounds blatantly anthropomorphic. "If it doesn't like look a human would make it, it's not a good design" is a... bad rule of thumb to say the least. Also very boring and unimaginative. Sure, ships in the shape of giant squids and rays aren't great, but what makes a great ship design great is probably beyond our current understanding.

That's a lot of words to say "If it doesn't look like a flying brick, I don't like it."

To be fair to Halo, Covenant ships are intended to be religious symbols and reminders of the power of the Prophets rather than effective military vessels. The Covenant military is intentionally portrayed as somewhat inept and only really winning the war because of their vast technological advantage. The Forerunner tech it's (more or less) based on is much more angular and "human-like". Normally at least. The Composer in H4 is an exception (and much like the rest of the 343 art, not in keeping with the style of Halo.)

"They always look bad" because if it doesn't look like a flying skyscraper, Spacedock doesn't like it. It's confirmation bias.

This time on Spacedock: I don't like that alien races don't have design conventions that mirror those of humans.

Useless spikey bits? Ummm excuse me But THE IMPERIUM OF MAN never puts useless spikey bits on top of our vessels we put an entire gothic cathedral on our ships because we love our GOD-EMPEROR VERY MUCH!!!

When someone who isn't an engineer tries to assert what designs are "reasonable"

OH BROTHER your forgetting the "MOST IMPORTANT" part of WHY the alien ship designs are the way they are, and it's "in-universe" answer is because of cultural psychology that shapes the design of the ships!

Aliens would have a different sense of aesthetic than us. An alien might look at human ships and say "Good grief this is space travel not sex, why so phallic?" Then they'd get to know humans and they'd be like "Oh, that makes sense". Where you see "useless tentacles" an alien species might see as common sense engineering, they might think the best way for sensors to be arranged are through tentacles, for example. What you perceive as "sensible military colors" might be to them glaring an gaudy, depending on their visual spectrum. I mean, an alien species might have trouble seeing parts of the color spectrum like pink. Their ships therefore would be pink if they were fighting each other. Even after they've met aliens their conception of what is militaristic might still be bright pink ships, they perceive pink as being intimidating. Or yellow with blue polkadots. Who knows.

When the insectoid species has ships that look like insects.

Human ships: squarebois

"It should be sensible and humans should be able to build it. No aesthetic shit."

Perhaps I misunderstood what you were trying to say, but I have to disagree with your assertion that ships with hard angles are more practical than ships with curves. In fact, it's quite the opposite, from an engineering standpoint.

Spacedock:

"The best non-human ship design is one that conforms with human design considerations"...

Square panels aren't intrinsically more realistic than other shapes.

"Ships don't need to be squids"

If I was to argue for the colorful designs or for the "spiky bits" and other generally useless aesthetics added to many scifi ships, it would be that they function similarly to ancient helmets with plumes and brushes and painted or engraved shields on ancient warriors. Does it serve a practical purpose? No, but it adds an aesthetic look, and could even be used to show status, class, or inspire fear and dread.

I disagree with you pretty profoundly on this one. First. as others have pointed out, round is actually more realistic and more functional than boxed. Second, on the one hand you talk about a lack of imagination. On the other hand, you applaud ships for being "sleek and stylized and having a great visual aesthetic". But that's a human aesthetic you're talking about there. There is no reason whatsoever why alien ships should appeal to a human aesthetic.