That's not 100% true.
If you don't have the paid season you miss out on the new Vex Offensive activity, the Vex Offensive weapons, the season ornaments, the new heavy exotic bow, and a handful of other cosmetic things.
It's like you are being willfully ignorant with your argument. If they didn't charge people for the expansion then there wouldn't be a moon for the F2P players to visit, so that argument is 100% bullshit. Pretty significant changes to the nightfall structure and PvP modes, that wouldn't be available to the free players if Bungie didn't have a paid DLC to generate revenue. Just because it is available in the F2P version doesn't mean it didn't cost Bungie to make those changes.
There is also a new raid which is damn good and an interesting exotic quest tied to it. New dungeon coming up soon.