Then we wouldn't forced into the trap were the servicepack/security patch actually does harm.
Incedentally, my company is one of those that will not touch any MS service pack or update with a ten foot pole until it has been internally QA'd and we have a lot of systems to QA.

A company I worked with took the same approach, until they started to get hit everytime a new worm came out as people's unpatched machines sitting at home VPN'd into the corporate network got hit via their Internet connections. Being VPN'd in those machines then infected the unpatched machines inside the corporate network. Now they have the policy of patching as soon as the hotfixes appear. They have lost far more time to not patching than they have from hotfixes breaking everything.