Opening a mailing list thread on this BIP:
BIP PR: https://github.com/bitcoin/bips/pull/173
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.