"401(k) plans usually lack a traditional pension’s biggest selling point: a guaranteed income for life."

The biggest "selling point" is also the biggest reason why defined-benefit contributions are fiscally unsustainable, and why state-sponsored pension plans will all eventually go bust (like in Illinois and New Jersey). By "guaranteeing" a certain payment for life, they lose the flexibility of being able to ratchet back overly generous benefits when the golden goose is in danger of dying. You simply can't afford to pay people a high percentage of their working salaries when they AREN'T doing any productive work - for 25, 30, 40, even 50 years in some cases (think of a firefighter who retires at 45 and lives until 95, all while drawing a pension). It is simply unsustainable.