Thousands of people have instant access to your "Sensitive" personal records. Who you ask?
Your ISP employees have access to your Email
DMV employees
IRS employess
Phone/Cell company employees
Credit Agencies employees, Equifax, TransUnion, etc
Your Bank/Credit Union employees
Your credit card company employees
Your mortgage company employees
This list could get long so I will stop. The point is, why sweat backing up your contacts to a web page. Even if someone looked at your contacts, who would care.
Microsoft's Privacy statement.
http://privacy.microsoft.com/en-us/default.mspx