The problem is that it is very easy to point and say "that's a bit rubbish" but an awful lot harder to actually come up with an acceptable alternative. Personally I agree that calibre (on Windows) is darned ugly. However as has been said many times I would rather ugly with the functionality than pretty without it.
Changing the icons to be consistent and more meaningful in some cases would not be difficult for someone who had the skills (sadly I have no graphic design skills whatsoever). Kovid has said in the past just submit them here for the peanut gallery to yay or nay and he may accept them.
However moving things around the screen in terms of layout etc is where it all starts getting controversial. As I see it calibre was written by technical users for the needs of technical users. Where previous proposals (well, one in particular I can recall) have "failed" is where they relied on dumbing down the calibre interface. Thereby making it harder to use the advanced features which many of these more technical forum users most regularly use.
It just needs someone who has the skills, the time and a thick skin to take on board any well intended criticisms and follow it through. However unless you have something to contribute in that regard, there is little point in poking it with a stick
