My account is getting charged everytime I purchase a module. DCS World is F2P with paid DLCs. You can't make up ridiculous comparisons to "other companies" (maybe give an example?) just so it can fit your narrative. There are plenty of F2P games out there, much bigger than DCS, and nobody is getting charged for core updates. That's the definition of free to play.
If you want to argue that "they could have released caucasus as paid DLC", then fair enough, but the original point still stands in that case. It's 2016 and they need the base package to be as appealing as possible. You can't do that with 10-year old map.