If everyone agreed, or most agreed, in the mining world to switch off their machines on a difficulty change period it should set to zero, then restart all the mining operations and everyone could have a bumper 2 weeks 
Yeaahh, that's not how mining works...though it's a fun thought experiment.
Problem #1) Who would mine the last block (#2016) to initiate the difficulty change? Even if "most agreed", the remaining miners (assuming there were very few of them) would take ages to solve the last block. No transactions would be processed on the Bitcoin network and the whole thing collapses.
Problem #2) As far as I've understood it, a change in difficulty doesn't happen based on what's happening on the last block, but rather the culmination of all 2016 blocks after the last change. To cause a drop in the difficulty, the average timestamps on the blocks would need to be greater than 10 minutes apart. Stopping at the last block wouldn't do anything to change the average of the previous 2015.