Re: Does Data have a soul?
It's more than just limited time. Aliens in Trek often serve the same purpose as the different peoples that Gulliver encounters in Gulliver's travels. They explore a single socio-political idea that is extracted out of the diversity of humanity, concentrated, and taken to its logical extreme. It therefore acts as a lens where we can see various what-if scenarios, at least how the writer would like us to think of those what-ifs.
If every alien species were as diverse as humanity, it might be more realistic, in a way, but less useful as a storytelling device.
I suppose so. If nothing else, characters the audience finds harder to relate to are useful in terms of introducing conflict into the story. If every character were easy to understand and relate to, there wouldn't be as many chances for conflict.
"He clapped his captain—his friend—on the shoulder. Yes, this man was very much like James Kirk, in all the ways that mattered." --Christopher L. Bennett-- Star Trek: Mere Anarachy, The Darkness Drops Again