- As time goes on, legacy transactions will be paying to increasing numbers of segwit addresses. The amount of legacy transactions will gradually shrink, so this is a short term phenomenon
- Antpool are keeping the average block size smaller with this practice, which has advantages too
- If pools were to consistently favor segwit over legacy, the opportunity to move BTC from legacy to segwit is reduced. Having a conservative small blocker mining pool like Antpool around ensures the freedom to switch to segwit
Let's not forget another aspect to this also; miners are beginning to designate bech32 native segwit addresses for their block reward payouts. This will create a big incentive to continue to use bech32 for any recipients of those coins, as there can be no privacy loss when using it.