Buildings were a meaningful MP sink and you practically developed your provinces with them. Building in bad provinces was not more expensive, but less efficient, which amounts to the same.
Lacking the development feature but getting the new building system, you are somewhat stuck. Except for forts, the building system should have stayed the same for non-DLC owners.
The new building system depends on the development system and its assumptions. As it is a core feature, locking one half is ugly.
Though, the development system itself is somewhat badly balanced, too.
I do like the DLC-model in general, but some locked features break non-updaters, which is a shame. Works much like an expansion, however - people without the DLC are functionally stuck around the previous patchlevel, as if they did not buy the expansion and their version did not get updated any more. Maintaining multiple versions (expansion levels or DLC combinations) will always be messy, though.