On my last flight, DL, I missed the safety instructions and was scared I would not be able to figure out how to fasten my seat belt.
Back to reality, if they kept the messages clear of all the clutter and advertisements then a more intrusive "dong" of some sort would not bother me. But I really hate being disturbed while I am a captive and they want to advertise their product, then thank every pax individually by name, sell credit cards and give you a totally random flight status. Oh, and tell me once more how to fasten a frggen seat belt.