indiscriminate niceness is overrated?

No. I am nice to everyone and dont except anything but niceness in return.

Maybe not always, but most of the time. Welcome to SW

Maybe occasionally but I disagree with that as a generalization

Being nice is important!

Indiscriminate anything is cause for concern

The motive itself can be a harmless one.
Say it just brings them a personal satisfaction to be nice.
What harm is it then?

Nothing is ever going to be absolute good or bad. Take the good and try ditch the bad.

Yeah it’s called ‘not getting bit in the ass by Karma’ 🙏