It's not the message that is annoying, it's the method. It's also boring and predictable. The next time you need to get someone's attention, be creative... be unpredictable... and don't be annoying.
If you're running a business, it can seem effective to blast your product to every person you know every time you see them. And you may find short term results, but ultimately you're going to become that annoying intercom system that everyone despises. You'll become predictable.
As an alternative, you may try building relationships with people. One thing history has told us is that relationships continue to work while intercom systems have become outdated.