Only in the eyes of some beholders.
My apologies for not responding sooner, this issue has been on my list to chase up for a while. The reason for the difference being observed on the rocky worlds is the change to the new material system - in theory this is more accurate as it uses the chemical properties to determine the colour (obviously I'm simplifying a bit here!), however the problem is that those colours were based on Earth standard colouration for those materials, and most of those are beige/brown rather than the colours you might observe in the myriad of other possible conditions. We're currently working on a more flexible material system, and this will necessitate a fresh balance pass on these. That's not going to be in 2.3 though.
Michael
I think a major problem in the lighting system is that the human eye compensates for lightning anyway. So even if you were on a world around a red star, your brain would still perceive white as white. The game engine turns everything orange-brown and us playing the game just see everything as orange-brown.
I think the amount of colour that comes from the star needs to be toned down, and everything made more white.
These worlds might actually be generated with quite a lot of variation in colour. But we're not seeing it because it's being illuminated by an orangey-red light most of the time (most stars are red or orange after all). It's as if the galaxy only has sodium street lighting...