you know you can play with the vanilla version any time you want right?
how?
Further to the other response you got to this question, if you go to EU4 in Steam, right-click on the name in your library, select properties, and select 'betas', you'll see there's a bunch of old versions you can load up (most of which, but not all, look to support ironman). It's worth noting that if you go to a version earlier than a release of a particular DLC, that DLC isn't likely to work, but in the context of your thread title, this is how expansions used to work (they used to stack - so we needed to get all previous expansions to play the more recent one).
So, kind of ironically, the issue with buildings and common sense is actually more like the old expansions than any other DLC set from Paradox yet

.
That said, I do understand the concern, given the size of the change in mechanics, and the limitations to building slots that arise from it, and I'm not sure I'm entirely comfortable with how it's been implemented, as I do think it was a large and more-limiting change to current players who may not have gone with the DLC. Some kind of in-game option to 'play the game the way it used to be' may have been useful, if relatively easy to do, or at the very least some in-game instructions on how to load up the most recent pre-Common Sense beta in Steam (I think 1.11.4?)
Edit: On the whole evil corporation thing, given you had the project lead come into the thread and provide a comment, on an OP that could have been written (far) better, I'd say that's a pretty good sign they're not one.