I would have stuck happily to a space-exclusive theme, but people were pretty enthusiastic about the hybrid "space temple" idea, so apparently we're giving that a shot. The point is, however, that it's intentionally looking like a castle or ruins because that's what people wanted to draw. Now, the two are not strictly incompatible... I refer you to Deckstar, my obvious source of inspiration, or Alien Temple ][, perhaps the only example of such the community's produced so far. Or even an image search for the words space temple on Google. Basically, when you take a space temple, which is apparently what people were enthused to draw, you get a temple with space in the background.

Is this necessarily a good thing? No, of course not. You could easily argue that it's an uncreative blending of the two ideas and that there should be more space aspects in the temple itself, not just stars and planets in the background. In fact, please do, or I agree that this won't be all interesting. But it's ever so much more productive to suggest ideas for how that could work -- specific tiles, constructions, etc. -- or even draw your own tiles for the set to illustrate what you mean, than simply to say that, without your having contributed anything, the tileset isn't going in the direction you'd like it to.

ETA: Since, you have contributed! Thank you!