For instance, I received one today from HMRC (my country's tax body). I had to log in to find out what the contents were, in this case it was just a reminder of how much tax I need to pay by the end of next month.

As it happens, I already knew this because the previous bill 6 months ago also included this information, but the message itself was unique and important. Certainly, there would have been financial consequences if I didn't act on that information.

I would have preferred to receive the contents by actual message rather than having to log in to read it, but that's not an option they offer. It's certainly not safe to assume it can all just be ignored.