The Adult companies are opposed (and boycotting) as they already have established brands. The Xtian groups are opposed due to it validating pornography (when they shouldn't be, easier filters). The mainstream companies are opposed as the 'prevent registration for $100/yr is a bleedingly obvious protection racket to avoid higher lawyers fees for disputes.
This decision was good for nobody except ICANN, its associates, and those behind the registry.
Wait for gTLDs in April 2012 to completely distort people's concepts of the www, make the lawyers happy, and yes, break some of my regexen ;)