Writing a proper
alien race, ie one that is really alien, is tough.
Heck, I saw that District 9's makers went with bipedal aliens so that they'd be more relatable to the audience. There was concern that if they were 4-legged or 6-legged, then audiences wouldn't ever really sympathize with them.
Or it might make audiences shy away.
The Distant Origin episode of Voyager is an example where Starfleet's finest Delta Quadrant crew wasn't able to find some clever way of outwitting a superior adversary. The Voth showed up, overpowered Voyager in no time flat, and easily shut down anything the crew tried to do.
It'd be like a person showing up at a hornet nest while wearing protective clothing and wielding three cans of Raid and
a Shopvac. The hornets just can't do anything to overcome that kind of advantage.
That kind of thing can leave audiences feeling like changing the channel, and we can't risk losing a single viewer for any reason.
What I meant is that the Universal Translator also translates implied meanings across known species. So "Warp 4" for species X might actually translate to "Warp 8" for humanity across unit conversion scales. The Universal Translator takes these things into account.
So much of our language requires you to understand a lot about how things are here on Earth, and in this Solar System.
Quick, how long is a year? How long is a day?
What if the aliens come from a binary star system and their planet rotates
very slowly, maybe like Venus, where the day is longer than the year?
Or a place where water never freezes - or
a place that doesn't
have liquid water at all, where our word "rock" would translate as "water."
It is of course just a plot device to make it all go quicker. (duh)
You'd likely have a lot of interactions where a few decades pass before two species could communicate effectively, and then they might find that they have nothing of interest to talk
about. That's assuming that they speak vocally, and that their language is compatible with ours in any manner. ("Wait, you don't communicate using a pheromone mister or by changing the polarization of the skin on your face? How...you can't...but...what??")
Or the
Enterprise bodge fix: Hoshi. Sure, just listen to an alien talk for several minutes. You'll be able to figure out how to synthesize the rest of their language from that!
A computer wouldn't be able to do that with just
our species, unless perhaps it was able to quickly simulate a probable history for us with an absolutely
absurd level of detail, meaning simulate the origins of life on Earth at the atomic level and pass it all the way up until you've got humans talking to each other.
"Ooh, I like this German word. But it sounds a bit weird at the end so I'll just hack off a syllable. There we go, better!"
Then a few years later it gains a Latin suffix and loses a consonant somewhere.
Or a Japanese word is roughly translated and spelled phonetically, and is also assigned a fraction of its original meaning.