While I understand that the conservatism the author refers to might be detrimental to the individual working alone, in a team environment it is actually an advantage. The module the team member is working on is likely a dependency for some other team, and any test-breaking refactoring---however beneficial it might seem---needs to be conscientiously approached and coordinated with other people. There may be very good reasons not to pursue refactoring at the moment, reasons that an individual narrowly focused on the module at hand might not be aware of.