Believe me, this is not a Microsoft only issue... ;-)
Microsoft Considers Opening Up Access to Windows Forms
"Burke acknowledged there are a few potential stumbling blocks that could interfere with making the WinForms source more widely available."
"The WinForms source — like all Microsoft source code — is loaded with comments that developers wrote into the product when creating it. And code comments typically include lots of four-letter words, politically incorrect references and disparaging comments about competitors, if not customers."
"In order for us to ship the code we need to 'scrub' the comments and make sure there is nothing bad in there. No swear words, no bad jokes on the part of developers, no references to specific customers, no geo-political faux pas."