Why are Microsoft Customers Scared of Criticising Microsoft?

gsfprez asks: "This article documents the stories of three Microsoft customers (organizations that voluntarily buy Microsoft products) who are clearly unhappy with the product offerings of Microsoft - but are simultaneously petrified of this fact being made public. My question to the crowd is not regarding the subject matter of the article: rather, I want to know what is it that could scare a company away from telling a product vendor that they are unhappy and merely *considering* not buying their next product? Fear of reprisal (in the form of a software audit) is simple extortion...no? More ethereally - do we actually live in a world where MS not only 'demands' you buy their new products, but appears to have people pissing their pants at the thought of doing otherwise?"