Why isn't full disk encryption from manufactures a slam dunk?

I saw a post today on the Security Basics mailing list asking "Why isn't full disk encryption from manufactures a slam dunk?"

I think the answer is that it is still rather new. The problem is its new so some people are waiting to see if its defeated by attackers. Others made recent investments in softwarae FDE. Dell just made the Seagate available in the Latitude line at the end of July. Give it some time. I expect within three years hardware FDE will be the norm.

I received a Dell Lat 830 with a Seagate Momentus 5400.2 FDE drive on Tuesday. I need to remove the software encryption the help desk loaded on their, but I should have some comments later this week.