they are talking about limiting the total amount you can have in tax shelted accounts. it's purely political. they don't want to wait for the taxes until you pull the money out. (taxwise it's a wash, now or later it's all the same) however, right now it is good politics to level the field and make it look like it's only fair that no one has too much when others have nothing. it's not fair that some have fat retirement accounts.
that term "need" keeps cropping up in the lectures we keep hearing. "at some point, haven't you made enough money?" or "i don't see why you'd need more that 3 million in your IRA."
It's also a prelude to meanstesting social security and medicare.
they don't want to wait for "their" money. call it receipt accelleration.