http://lists.linuxfoundation.org/pipermail/bitcoin-dev/2016-March/012489.html

Go go Core!
Quote from: LukeJr
We are coming up on the subsidy halving this July, and there have been some
concerns raised that a non-trivial number of miners could potentially drop off
the network. This would result in a significantly longer block interval, which
also means a higher per-block transaction volume, which could cause the block
size limit to legitimately be hit much sooner than expected.
[...]
To alleviate this risk, it seems reasonable to propose a hardfork to the
difficulty adjustment algorithm so it can adapt quicker to such a significant
drop in mining rate. BtcDrak tells me he has well-tested code for this in his
altcoin
Hahahaha concerns raised that a non-trivial number of miners could potentially drop off
the network. This would result in a significantly longer block interval, which
also means a higher per-block transaction volume, which could cause the block
size limit to legitimately be hit much sooner than expected.
[...]
To alleviate this risk, it seems reasonable to propose a hardfork to the
difficulty adjustment algorithm so it can adapt quicker to such a significant
drop in mining rate. BtcDrak tells me he has well-tested code for this in his
altcoin

Go go Core!
In all truthfulness, I have always wondered the reason for the 2016-block difficulty adjustment. A finer-grained adjustment seems just natural to me. Though I've never looked into it. What are the arguments against a more continuous adjustment?
(The four-year halving always seemed funny to me too. Done merely for simplicity of implementation?)