How to change the theme of Office 2013

Looks like MSFT decided not to listen to the customer base since Office 2016 is on the horizon. Sure hope Office 2016 offers more theme options than Office 2013 because these are horrible.

Please listen to your customer MSFT.

I recently had my IT department "upgrade" my Office install to 2013.  I was encouraged by the numerous new features of Excel 2013 (mapping, PowerView, etc.)  Immediately however, I found my eyes very sore from using the applications.  Excel 2013 is very difficult to view for long periods of time.  There is little contrast around buttons, lines, etc.  If I was using the application on my phone to calculate some simple formulas, OK.  But if I'm using this application 20+ hours per day, not happening.  I then moved onto Outlook 2013.  Unbelievable, does anyone at Microsoft care about the customer or heck even it's own financial results?  I now understand all the negativity around Windows 8.  Let me tell you, Office 2013 look and feel is worse.  

I have had my IT department remove Office 2013.  I have requested that Office 2013 NOT be installed in my departments machines (we have 150 people here).  There is no way I could take responsibility for allowing my co-workers to utilize this awful product.  I spent several hours searching for some sort of 3rd party skin software before coming to this decision.  There is none.

I then looked forward to Office 2016.  Certainly, MS listened to it's customers right?  Wrong, the 2016 preview is just as bad.  The 'Colorful' theme truly pathetic.  Seriously, the reviewers at CNET are only going to use the software for a few hours.  They'll give it a good review based on features sure.  However, the end users, the ones that actually have to use these products day in and day out are not going to be happy.  Looks like we have to stick to Office 2010.  Until a competitor comes along as takes a big bite out of this product line.  I no longer consider myself a fan of Microsoft (I know, I know, how did I last so long - because Office was always good for me that's why...)

+1 for "hate the new themes."  There is almost no difference between the 3 options.  I miss the dark theme from 2010.  

Also I don't like how everything blends into each other with the semi borderless design.  I like to know where my interaction points are.  

Sad that I'm reply to your post almost 3 years later and the problem still exists.

Office 2010 looks good just go back to that look, I cannot stand the look of Office 2013 or Windows 8 for that matter, I get that shades and dimensions take up memory but I could do without the online interaction all of the time to get my memory where I WANT to use it.  Most of my clients don't allow internet access as they want to protect their data and systems as much as possible and the more people who are "online" the more likely they are to bring in viruses.  Somehow you need to run these things by your real end users before making these decisions.  Like Vista was very pretty, overkill on the prettiness, XP and Windows 7 about right and then 8 awful and Office 2013 looks just like it, awful.  People who really use these products don't get to spend much time playing games and surfing the net so we need to have something to work with that doesn't give you a headache and eye pain from looking at it but doesn't take up all of the memory with how pretty it is.  Those of us who have to use our computers for work, Windows main users btw, don't want a lot of change, just improve on what we have, we don't have an abundance of time to spend re-learning systems for the sake of change.  That is why so many people have stayed with XP, good product for working people.