Ok, yet another new poster registering to kavetch about the flat UI - here's my spin on it:
I've been involved with computers since the mid 1970s - way before most people even knew what one was. Built an IMSAI, cut my teeth on a TRS-80, etc, etc, etc. Needless to say, I've seen all kinds of fads come and go (remember when Micro$oft wanted their OS to look like the web?), self fufilling prophocies (C language), etc, etc.
My speculation is that the dev team has a case of religion. I've seen lots of religion in this field over the years - indeed, I had a company "shot out from under me" because they ignored reality and pushed their religion. Another good example of religion is Steve Jobs and his one button mice - when Apple finally threw in the towel on the one button mice that everyone was throwing away, they got around the religious objections by designing a 2 button mouse that looked like a 1 button mouse. Whatever...
There's a chunk of upper management at Micro$oft who found themselves on the outside looking in when their religion didn't pan out with no start menu, etc, etc, etc. Now we have ccleaner that is becoming bloatware with features no-one asked for (active monitoring, who needs/wants yet another daemon running?), but at least such items can be ignored and/or turned off as desired. Except one: The ugly UI. Methinks they're digging in their heels on this issue because someone bought into Ballmer's belief system lock, stock, and barrel - never mind that Ballmer is no longer at Micro$oft.
Whatever. They'll either change it, or they won't. The program is still usable, albeit hard to see. Apple and Micro$oft both are trending towards low contrast, hard to see UIs, even though its been proven time and time again that white backgrounds with dark text are NOT a good display choice for technology that emits light - as virtually all computer displays do. I've watched the PC industry ignore and/or bastardize every standard they've ever touched - but I digress.
At the very least, I'd ask the developers to at least use better contrast and less bright backgrounds (read: NO white). Microsoft's own design rules suggest inheriting whatever the system settings are (NOT that even M$ follows consistently).