From a practical standpoint, the new MyRA accounts don't make any sense. That's because the target contribution demographic doesn't have any money left from their paychecks, even if they were so inclined to contribute to such a plan. Even if they did have the money, it is obvious to even the dumbest hillbilly that their "savings bonds" would be destroyed by inflation over time. Furthermore, as far as I know you can open a Roth IRA - a more flexible plan with fewer limitations - with low or no fees. So what possible purpose could the introduction of such accounts serve?
All holders of tax-sheltered accounts are in bed with the government, like it or not. While such accounts have only been nationalized in effectively insignificant countries, that merely serves as a model experience for much larger countries. No government genuinely believes that you can manage your retirement account(s) better than they can. Especially if they become in dire need of capital injections.