I like what you are doing with the villagers. The pre-1.14 game encourages treating villagers poorly. Modifying the game to encourage treating the villagers kindly seems like a good change.
I also understand the technical minecrafters still need a mechanic in game for getting large amounts of iron. It seems like there is already precedent for this kind of farm as seen in the Witch farms dropping redstone and the Zombie pigman farms dropping gold in various forms.
My suggestion is to make the pillagers drop iron at a reasonable rate. The pillager towers are a reliable way to get pillagers to spawn and if they drop iron like zombie pigmen drop gold, it would make for a compelling way for technical minecrafters to get iron from a more 'ethical' source.