Any idea why the custom logo in the O365 theme must be 200px wide?

We had a 99x50px logo previously and I missed that it's now required to be 200x30px.

I just wanted to reduce the height a couple of pixels but it didn't take the new logo due to the enforced constraints so now I have to upload a logo file with our logo in the middle and a lot of whitespace on each site which doesn't look good.

Any information on why we must have a 200px wide logo?