Imagine the state of DT without graphical update. Theyre smart enough to recognize they need to add that to DT to make it better. Could the lore be purposely boring to make sure the next expansion will be better? Maybe. Gatekeeping contents and releasing them in batches will ensure the quality is spread out. They wouldnt have released graphics update in ShB or EW because the story and everything else already carried those two.

Call it a conspiracy theory if you like but it makes a lot of sense business wise. Like when you know your newly made car model is not as impressive in the terms of performance improvement from the previous one, you just slap never seen before color exclusives to add value to that model. Could they have added those colors to prev models? They could have but they didnt have to.