The 401k being 100% yours is a somewhat significant downside, too. It means that the funds get transferred to your heirs on death, diverting funds from supporting retirement in general. This can be counteracted by purchasing an annuity, but that usually isn't the route taken by retirees. Overall, it means that saving for retirement is more expensive than it needs to be, since you're also effectively saving for an inheritance too.
The pension, on the other hand, effectively collects mortality credits as beneficiaries die and distributes them to survivors.
The ideal retirement system would be effectively some sort of actuarially adjusted tontine. Nothing gets left behind when you die - instead, it gets split among surviving retirement savers in an actuarially fair manner.