I have operated a flight before whereby the autopilot wasn't working correctly and so the flight crew had a lot more work to do and as a consequence had no time to inform the pax and they weren't about to worry everyone by saying that they had a problem so it's was a quiet sector from the front. Their workload had suddenly gone thru the roof for the poor guys and although it wasn't an emergency situation, it just meant they had no time for niceties.
Maybe your experience was down to something like that. Something you were totally unaware of. Something that was important! Not hearing a PA isn't the end of the world and sometimes you need to think outside of the box. Making comments to the crew about what goes on the other side of that door which nobody apart from the pilots is aware of, is pretty rude and will do yourself no favours. Coming on here asking if it is "inexcusable" that you didn't get a PA is going to be met with a plain and simple, no and also the sort of comment you have received. Surely you can expect nothing else?