Microsoft cryptographer: There are no back doors into Vista

By way of ZDNet reader Derek Flickinger comes VNUNet's Iain Thompson's report:

A senior cryptographer working for Microsoft has vehemently denied that the firm is planning to compromise the encryption functionality incorporated in its forthcoming Vista operating system by adding a backdoor. Niels Ferguson, a Dutch cryptographic engineer and consultant who currently works for Microsoft, has written in his blog that there are no plans to provide a secret means for law enforcement officers to access encrypted data. He added that, if pressure came for such a system, Microsoft engineers would either go public or withdraw the platform's encryption feature altogether.

Referring the Microsoft's encryption technology known as BitLocker (the technology that could keep law enforcement agencies from getting at the contents of a hard drive or thumb drive), Ferguson also wrote "Like any security technology BitLocker has its avenues of attack and law enforcement should know about them." 

I'm not making this up.   So, if it has avenues of attack, why bother?  Or is it just to keep casual hackers at bay? (in other words, why bother?)