It's a little more understandable with some of the services they provide, like party chat, but what gets me is that I feel like it was a bait and switch.
I didn't need to sign up for a beta of Nintendo Online Services or anything, I signed into my Microsoft account and I could play Minecraft online on my Switch. Unless you read all the latest Nintendo news there would be no way for you to know that would change. I wouldn't have re-purchased Minecraft on Switch if I knew they would eventually disable online play unless you pay.