"And no, there won't be a non-steam version.. We had a huge forum-demand for a non-steam version of CK2, and it had an even less percent of the market than we had expected. "

Why EU4 requires Steamworks. by Johan (Paradox)

There are several reasons for only making a steam wrapped game build.

1) Maintaining multiple versions of the game for testing and distribution is a large cost in time and attention for us as a development studio. To be frank, we prefer to use the time and energy to improve the gameplay experience for the gamer, add new features and updates/patches to the game for free for the gamers - rather than using the time to support several different game builds.

2) Steam is very easy to work with when it comes to creating patches and updates.

3) Steam has pretty much the entire market, so spending 50% of the testing time for patch deployment for a tiny fraction just doesn't make sense for us.

4) A large chunk of customers at other online retailers buys steam versions of other games, so our hopes is that we won't lose all those customers, but that they will understand why we have decided on steam only and stay with us.

5) Customer support costs. A large majority of our customer support comes from people that is not on Steam that has trouble installing things correctly.

6) Steam provides a lot of technology that makes it easier for us to develop games, which makes us able to focus on the quality of the game instead of making our own network api.

We aim to support Steam workshop, Achievements and other things in Europa Universalis IV as well, but that was never relevant to our decision to go steam-only.

That Europa Universalis IV will be steam only was a decision we as a development studio took in a strategy for the future to create better games, being able to support the games for a very long time and ongoing add new free content updates and patches for all you gamers