A Few Science Fiction Clichés to Avoid

Although I am an avid fan of science fiction, there are certain overused tropes within the genre that cause me to cringe. Here is a list of a couple things that I can’t stand seeing any longer.

Bipedal or humanoid aliens 

While I will not deny the possibility of other lifeforms in the vast expanse of space, I often grow tired of alien lifeforms that are near-identical to human beings. The usefulness of this allegorical construct is obvious — a unified alien race often represents certain exaggerated aspects of human behavior. Alien races often serve as thinly veiled examples of the best or worst aspects of the human character.
Standard plots that exemplify these characteristics are as follows:

• Aliens are too evil to recognize the value of humans, and wage war against them or attempt to enslave them. The evil aliens cannot see us humans as the flawed but ultimately enlightened beings we truly are. This ironically enough, is usually resolved through full scale war and eradication of the alien beings.
• The human race is too evil to recognize the value of aliens, and wages war against them or attempts to enslave them. This often results in a plot resolution delivered by the human protagonist who can see the aliens for what they truly are.

I have always wondered why it is that aliens are so often presented as humanoid in appearance. If there were another planet, capable of sustaining life, which apparently there is, what are the chances that the creatures on that planet would evolve in a way that correlates with human features? There is an extreme diversity of sentient creatures on this planet adapted to regionally diverse ecosystems.
The chances that another planet would offer similar evolutionary and ecological conditions to create a being perfectly correlating to homosapiens seems slim. It is more likely that other planets would produce  biospheres wholly disparate from that of earth. As a result, planetary organisms on other worlds would be unrecognizable to anything seen on earth. Perhaps sentient aliens would be so different as to make intercommunication impossible.
Militarized Space Vessels or Stations
This is more a standard in television shows. There is a dashing captain who directs his diverse crew of humans and bipedal aliens through an exploratory journey in space.

The plot arcs generally revolve around:

• The command of an overruling space confederation, whose member fleets resemble 20th century naval crews. Their task is to explore or police the galaxy, making the vast reaches inhabitable for “civil” beings.
• A back-story involving a formerly great space empire pitted against hostile beings who are culturally barbaric. The plot arcs revolve around an attempt to restore the empire to its former glory.
• The strained diplomacy between allied good guys and fascistic or warlike beings who lack human compassion.

While some of these concepts have been beautifully expounded on in novels such as Dune, in general space militarism has been done to death. Perhaps a more interesting concept would be a more exact look into the mechanics of space travel.  What are the economic and engineering specifics of space travel? What are the goals of the military? Why are they performing altruistic actions and at whose expense?