Opening a mailing list thread on this BIP:

BIP PR: https://github.com/bitcoin/bips/pull/173
Code PR: https://github.com/bitcoin/bitcoin/pull/6451

The general intent of this BIP is as a minimum viable alternative plan to
my preferred proposal (BIP 100).

If agreement is not reached on a more comprehensive solution, then this
solution is at least available and a known quantity.  A good backup plan.

Benefits:  conservative increase.  proves network can upgrade.  permits
some added growth, while the community & market gathers data on how an
increased block size impacts privacy, security, centralization, transaction
throughput and other metrics.  2MB seems to be a Least Common Denominator
on an increase.

Costs:  requires a hard fork.  requires another hard fork down the road.