This was suggested when maplantis was going to phase out. Since that is no longer happening its no longer a problem.

I'm so happy Maplantis is living. No disrespect to SEN, it is my 2nd favorite mapmaking site, but I like Maplantis a bit more. One of the reasons for this is the theme/skin. I like the skin/theme here, but IMO Maplantis layout/skin/theme > SEN layout/skin/theme.

I fully intend to change your opinion on that. Syphon is planning on helping .
But if you like blue (I like blue) and you want a different skin, why not make it yourself? Change the css colors to blue, change the images to blue (preserve file names) and upload me a copy. If nothing else, just for shits and giggles (assuming yoshi doesn't care, like if maplantis would phase out in the future or something).