I've been working as the creative lead of Paradox since 1998, and am responsible for all the PDS games so far. I've also been in charge of everything related to our development until spring 2015 when I took a step back to just focus on the game design as we had grown too large for one man to handle everything.
Just to correct some errors in your post. Your premise of differences between "old" and "new" paradox is wrong.
Game Design This have always been "gameplay > history". There are posts about me explaining that repeatedly before HoI1 was released on our forums.
Game Mechanics These work the same as they have always been. Far far more complex today, with far less abstractions.
Target Markets I've never cared about such analytics. I make games that I want to play myself. Empirebuilding games on maps with historical flavor.
User Experience This has changed dramatically, while we have made features far more complex and deep, we've also managed to make UI that are not total shite these days.
DLC Policies Eh.. There is not a single 20$ expansion we made back in the days that would ever have enough features to be enough for a 10$ update these days.
Player Count I dunno about you guys, but I've almost always been thinking MP, from day 1. 50% of the development budget for EU2 was spent on making a decent network architecture, and all patches done after the first three months was due to me playing MP and tweaking the game on weekends.
But what has truly changed since the start of CK2 have been the following.
QA Not just 1 person at 50% testing the games, but 2-4 people working fulltime at it. Bigger Budgets Instead of making new games in 9-10 months on 2 programmers, we now have far bigger capabilities. Dedicated AI Developers Never had that before EU4 was released..
Victoria 1 me and Doomdark coded in 8 months, with 1 scripter and 2 artists. And I was managing the teams, coordinating betatesters, and patched hoi1 at the same time.
These days, a single 4.99$ expansion for ck2 have multiple times that development budget.