Remiss is a needy needy word, at least in modern spoken English. I’m sure at some point years ago people actually used “remiss” on its own, actually using it to describe a state of carelessness or negligence. In fact, this definition lives on in its very useful offspring, remission.
But today, people do not say “remiss” without also saying “I would be … if I didn’t” as in “I would be remiss if I didn’t…”. Remiss needs SIX other words to survive. And there are many perfectly good substitutes that can be used almost interchangeably:
“Remiss” is on life support. It has lost all or most of its meaning and is only kept alive by the will of the words that surround it. I say it is time to let it go.