Eer, I don't get it, why wouldn't I want a 401k over a pension?
You can't trust pensions. Companies can go bankrupt, and even governments have been going bankrupt and have renegotiated pension plans. I'd much rather slowly tuck away a portion of my own income and have it be labeled as mine, rather than have it be a future debt on some organization's account book.
Replacing existing programs with "free choice" is a well-worn playbook. See also: pensions vs. 401k plans.