My response to the "meta" problem is essentially "screw it". If the current "elite" are affected by worrying about a DNF, then they'll have to suffer the consequences and a new breed of cubers will come through that won't be affected by it, and will be able to achieve optimum times regardless.
On a side note, personally I do not think many cubers would be affected by changing +2 to DNF except in circumstances where they already have a DNF (or doing mean of 3, but seriously, solve the damn 6x6 before you stop the timer, you've already had almost 2 minutes to get it right). But if they are affected, other cubers that aren't will be able to reap the rewards of not DNFing. Tough luck, grow a pair.
As for the "place it or drop it?" problem, the response is simple: if you wish to take the risk to get a slightly better time, go ahead, but the WCA is not going to cuddle you while you cry in a corner if your cube "accidentally" makes a turn as a result of that risk. It's not about banning risk taking, it's about having a solved cube when the timer is stopped. How the cuber goes about achieving that is entirely up to them, and if they wish to risk a DNF by throwing their cube across the room in the process of stopping the timer, that's the risk they take.