You might be providing a service to people who would like to know what part of the chain broke. If hosting company A fails all the time, and that's visible to me as a technical user of service A, I would avoid hosting company A for anything that I happen to host. I'm not the average end user, but that information is still valuable to me, and I would think less of hosting company A, instead of service A.

By Heroku not listing when its their downtime, they are insulating their reputation as a hosting company from end users, at the expense of the customers already using them. It's a little shady.

I agree that the average end user would probably not care, but most not caring does not mean it's not valuable information to some people. So I see where the original poster is coming from.