I'm sure Bungie didn't seriously think that people would be excited about getting less game for the same price just because a DLC comes out and locks some of existing content behind it. From what I hear though, Destiny one did the same thing with Taken King or something? But I think it also had a lot longer of a time from coming out after vanilla Destiny before it did, if it did. This game is less than 3 months old and is pulling something like this.
Lol game barely out for a month and half on pc, gets level cap increase so people who buy the base game can't even access the content before the dlc went live because entry scaled up....so if you want to do the content you were doing before the dlc, gotta cough up 20 more bucks!
In all honesty, you can't really count Bethesda as the 'savior' since they've pretty much re-released Skyrim like 4-5 times. The only real reason they aren't capitalizing on stuff like this is because multiplayer isn't really their thing unlike EA/Activision or even Ubisoft. They make story driven single player games which are arguably better than the aforementioned so its not surprising that they will continue to do. Lets not forget they are trying to do their post-transnational garbage as well by charging for mods for a game that were free until they realized they could get enough money for them
EA said it themselves and its obvious that other publishers think the same way, single player games dont pull in as much revenue as mulitplayer titles simply because of post-transactional revenue. Its already bad enough that you pay full price and then pay more for dlc and companies still dont feel that is enough. They want you to pay for the game+dlc+store stuff to make it into a p2p experience. Personally I dont know how to fix it because people will always want more money if they can get it