Somewhere the developer answered this question. If the main game changes (for example, the combat system), then it changes in the DLC, and this leads to new bugs. Therefore, they decided to separate the main game and the DLC.
We understand that, but what
sexypeanut perhaps tried to say was, why this DLC or as was knew before as Special Season stories don't becomes gradually inside the main game as part of the normal development of the game?. A thought that i share and i was thinking it would be in the future. It's like making 3 whole games with two of them just for a season celebration that can be part of the main game as secret missions that can only active and progress until some requirements can be achieved or something like that. So, you have secret quest for the gamers who are obsessed with the 100% of completion and the perfect excuse to develop this secret missions until next year without making another whole build just for that or build a separate game for that with their own bugs, Jesus... If you are a Patreon and you are reading this, for God's Sake, copy & paste this shit i wrote please to them.
Or do we talk about a different "DLC" here ?
Pal, from the beginning this was builds released for celebration seasons, specifically for Halloween & Christmas, originally came as a separate adventure from main story, being part of the build of the main game, but now is becoming annoying the attention for this every year instead of the development on Main Story. At least, for me...