99% of us don´t have the nerve to discuss such an Child-Garden-Question. Fact is that if Romero wouldn´t bring in more Content / Features etc. for Empire of Sin for the PC and the other Platform, then it would be not in Steam and other similar Platforms buyable as well as orderable anymore.
Now to the Reasons, why some Games are growing slower and others faster:
1. We don´t know where the Romeo-Dev-Studio have it´s Main-Office and evtl. outsourced Offices. It could be in the Ukraine (like Frogware with the Sherlock Holmes Games) or in an Country, which is in Danger about the Situation in East-Europe. Many Development-Studios in Europe have their Offices there [Hungary, Ukraine, Slowakia, Tshech etc.).
2. The longer under the hood cooking Unity-Crises for all Development-Studios incl. Publishers and End-Users (us Gamers). The Dev-Studios all over the World are overthinking to use the Unity-Engine and there Romero Studios, HBS, the City Skilines Devs etc. from the Paradox-Partner-Studios are concerned too. In that Case it´s no surprisse if f. e. the Terra-Invicta-Developers, Empire of Sins-Developers and many others which work with Unity hold on the Programming of an Base-Game, DLC, Patches, Base-Game-Upgrades etc.
3. And esp. if the slow thinkers don´t have grasped it: We End-Users are to 100% concerned (Unity will ignore our privacy protection and send the Company what Games we have installed, which get done with Unity) as well as we have to pay the special Fees (means Products get expensive, which belongs all Games and DLCs which get done with Unity).
Esp. the Points 2 and 3 the Developers / Publishers don´t wanna do to us End-Users. In that special Cases (all 3 Points) it´s fully normal that we Gamers don´t get new Content / Features / Changes / Upgrades. The worst thing is: If you begunn an Project with an Game-Design-Engine and did some DLCs for it already, it´s not easy to change to an other Game-Design-Engine. Either you have big Quality-Losses or you have to Reduce drastically already implemeted Features / Contents etc.
I suggest about the ongoing big Crises the last 4 Years, that we have to bring a lot of patience until the Game-Engine-Crises with Unity get solved or you all have to pay 20 or 25% more for Base-Games, DLCs and similar which get done with Unity or Refited older Open-Source-Game-Engines.