Whenever aliens are portrayed in a movie they are almost always an advanced society. They have the technology to travel light years. They are coming to destroy our world.
So why are they all naked?
Even the good aliens are naked.
E.T. can make a universal phone to call across solar systems but doesn't wear a pair of pants?
Then there is the crazy part. In the future, when we Earthlings have managed to acquire some technology to compete instead of going naked, we all wear matching outfits.
I understand the whole Garanimals vibe we got going on here, but really?
And what is with the one piece outfits? Is that really efficient for peeing in space?
Oh my goodness! I just got it. That is why aliens are always naked.
As you were.