In addition to security there is also the ease of maintenance that you gain by eliminating windows. But security alone should be enough to force the decision by insurance companies offering 'hacker insurance': Time may go by and the name may change, but it is still the old NT kernel underneath.
The Vista series is as vulnerable as XP. That includes Vista 7 and Vista 8. Every few months you have vulnerabilities that affect the whole zoo. On top of that you have a thriving ecosystem of malware flame and Conficker. New malware arrives and joins the old which never really goes away. It is the whole system that is weak, not just the pieces. Not even new, unready systems like Haiku-OS have that. The only way to leave it behind is to leave Windows behind.
No, the only real change since more than 10 years ago has been how M$ has been gaming the vulnerability reports and CERT. Even the shills and astroturfers defending M$ are nothing new.