I was very exiting when it's announced that IR will return to the pop mechanics. But after reading the latest dev diary on pop I'm disillusioned.
I discussed a lot with other pdx game fans and reached the same conclusion that, Johan doesn't understand why people are excited about POPs and what people want from a pop system. Speaking for myself, I love POPs because Vicky2 experience in which pops are fluid, dynamic and detailed. They have thoughts, production, needs and social mobility, and nearly everything happens gradually just like real life, all achieved in an outdated version of Clausewitz engine.
So when IR is announced, i naturally hoped for something similar. Some aspect can be simplified, like pop issue isnt that much important in this time period, but at least there has to be dynamic promotion/demotion since that's how it worked in classical time. As a slave, you can buy your freedom with saving and advanced into the freedman class. As a citizen, you may be sold into slavery due to debt bondage and bankruptcy. In Rome, freeman could serve in auxiliary unit to obtain citizenship. All this happens as a gradual progress, like "this month X promoted into freeman" in vicky2. Laws in this era were often introduced to control the social mobility - check Augustus' law of limiting slave emancipation, the Athenian law of abolishing emancipation and debt slavery - and i expected players able to do so, as a mean to indirectly affect the promotion/demotion process.
But what have Johan presented to us? a dead, static world, POP have no real income and expanse, happiness determination by arbitrary factors , and absolute nothing would happen without player/AI governmental direct interaction, that is to say, mana investment. POPs wont promote or demote by themselves, they can only be promoted with 10 mana per pop. They wont be gradually assimilated into the dominant culture (despite that's the exact definition of Romanization), but instead, spend some religious mana to convert pops to your state religion. Does it mean even the traditional conversion rate mechanic is ditched as well? I'm not sure but it's heavily implied so.
I'm fully aware that i cant speak for everyone, however many would agree that Johan doesnt understand what made POPs great. He presented his vision of POPs, which is disappointing to me and many people I talked to. People wanted a return to POPs (so many EU4 mods made a POP system, with real dynamic promote/demote mechanics), so Pdx say they reintroduced it in IR, which generated so much hype. But it turns out it's a mana-driven static system, instead of a living dynamic system many people hyped for.