Excellent blog. I totally agree. As both a project leader and team member, I've seen so many perfectly good collaboration systems go to waste, while everyone emails each other and tries to manage their email threads and supposedly shared documents.
You didn't even mention the other big benefit: individuals don't have to fret as much about backups; presumably, the content/document management system is getting backed up more religiously than most personal backups.
And the bottom line is this: all those documents, annotations, and other content are company assets, which need to be effectively shared and protected as much as the hardware used to create them.
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