The worlds are barren of style and substance. I can't put my finger on what it is, a combination of rarely seeing another person and general lack of ambiance. Getting exhausted in knee deep water is a cool "feature" too.
Plus they've created these planets that you're going to enjoy for maybe 2 levels before heading to the next one. There's no reason to ever go back after you leave.
They could've just created this game with warzones, the Fleet, and Ilum since that's where everyone ends up standing around in the end.
Some people are happy with sub-mediocrity, some expect more.