Before the eShop closes: should I get the DLC for BotW?

Speaking as someone who typically does not like to purchase DLC for games, I'm debating my options here and have decided to ask for some input.

On one hand, I don't like to support the concept of releasing DLC for fully-released games (and especially for half-baked games either). I also probably would not be a fan of the motorcycle, given that I think it takes away from the original game design by being a relatively "free" / "no risk" way to travel quickly.

On the other hand, I've not spoiled myself on the new story bits, and I would like to experience it. I'd also probably like to try Master Mode, I do like difficult modes in Zelda games, and I am excited for the new challenges in there.

Finally, some random questions. Does starting Master Mode mean I need to start a new file that will replace my original one? Is the DLC necessary to truly "100%" BotW? And finally, would you say it was worth your money?