Maybe its the lightning network?

It is early to say that but what if they just don't want to lose the on-chain customers?

I mean if LN gets adopted widely, only a few will be using onchain transactions. That means a direct loss of income for miners. What if they stopped spamming so they can be competitive to LN to not lose fee income?

Fee Income from 10sat/b txs is still better than nothing, right? If that's the case, core team just scored another one.