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" b
To add to the annoyance, the icon for Microsoft Office is the (dumb) one for Office 2013 - even if the version installed is 2010. Somebody at Piriform sure has a bad case of "religion" - but this too shall pass.