Yes, the 'one-and-done' scenario is bad, but in practice a 3-team round robin is almost the same thing. In a two-game stage with teams of wildly varying strength, inevitably one game will emerge as being pivotal. 

The only way this would make any sense whatsoever would be if the 2nd round (of 32) was still a round robin, which would extend the tournament's length.

In the sudden-death Round of 32 scenario, you have the same number of games per team (for those that make the 32), but against weaker teams. 

The only way this makes sense is as a cash grab. Of course you can win an election on this idea when there are more nations that have little chance to make a WC, and they get the same voting power as the top football nations. Go FIFA!!!!