I think there's a time and a place for PA's from the front. My personal opinion is that the most you normally need is two - a welcome from the driver for them to introduce the crew and give me any update on departure time / expected arrival time, and then a second update with about 30 mins to land. Beyond that I want to stick the telly or radio on, sit back and switch off and not be interrupted every 5 minutes with an update. If I want to know where we are or where we are going I can look at the moving map.