Sci fi planets

I read a lot of sci fi books, watch a lot of sci fi movies, and consider myself pretty well versed in the genre. There's one thing that I find very interesting, and that is how the other planets we encounter almost always tend to have just one uniform climate and the land features are the same across the planet.

Let's take Star Wars for example, since most people can relate to it. In Episode IV the first planet we see is Tatooine, which is entirely desert. The only other planet we get to see in that movie is Yavin 4, which is actually a moon, but still it's entirely jungle. Moving on through the series we see Hoth, which is all frozen and snowy, Dagobah is all swamp, Bespin we don't really get to see except the clouds, and Endor is another moon which is all forest.

Sure it can get more creative depending on the athors. Worlds that are entirely ocean, some with no continents but lots of mountains sticking up surrounded by water, some are just entirely like Hawaii (which would be awesome). Gravity can be different, there can be strange weather features, and obviously the animal life will vary, but this still tends to be uniform across the entire planet.

So why is it that Earth can have such a huge variety of climates and land features, but all the other planets we imagine don't? Do we just not have the imagination for it?

Maybe it's just our idea of travel and going to new places. Right now we live on one planet, where you can travel around and see various climates and land features that are much different from what we're used to.

Then in the future we imagine ourselves traveling not to different places on one planet for vacation, but to different worlds altogether. Well what would be the point of that when every planet had such a variety like Earth; where you could spend a lifetime just seeing everything on the world you're already on? They are basically expanding our own planet into a galaxy, where lightyears in a spaceship is analogous to hours in a plane, and where other planets are analogous to other timezones.

I'm not sure if these sci fi writers know it or not, but I think it's just human nature that makes us think that Earth is perfect, and no other planet can possibly be like it. I mean, it's our planet after all, and while nobody actually knows how it would be to live on a different world, I don't think we'd entirely feel at home anywhere other than Earth.

Not to say this takes away from the experience of a good sci fi. Sure it may be a little unrealistic, but sci fi is obviously fiction anyway, and I don't think I'd even want to think about how long a book would be if it had to describe every planet when those planets are each as diverse as Earth.

Does anybody else notice this or is it just me? What do you think?