Here's a crazy hypothesis:

Maybe Gavin realised where we're headed and didn't like what he saw.

With proposals like the Bitcoin Lightning Network the blockchain could one day only be used for a handful transactions per day, for settling big balances between major offchain micropayment processors.

Maybe he didn't like that idea and is trying to scale the blockchain to avoid it becoming redundant.

If that was to be the case, then the detractors who claim bigger blocks will centralise the network don't realize that it's actually a potential fix for avoiding even bigger centralised offchain silos.