The notice on the seat says it must be down for the security briefing. Nothing about take off and landing. I certainly put it up as soon as the briefing is done and haven't had any complaints. Once it's up I'm in my own little world and that's how I like it.
I fly BA because I fly frequently from the UK to many worldwide destinations, so they're the only logical choice for getting status benefits such as lounges. I spend a lot of time in the LHR lounges and I find them very good.
I also like the generous hand baggage allowance (23kg to all - not 7 or 9kg for all as many airlines do) which means I often don't need to check my bag. So even in Y with no status someone can check 23kg and carry 23kg (subject to sizing regulations of course) and I think that compares pretty well with most airlines.
I'm surprised you found CC rude on the headphone issue. I've seen CC ask people (me included!) to comply with this many, many times and the only times I've seen any kind of sharp behaviour has been when the person didn't comply with the first couple of requests. But I guess anyone can have a grumpy day.
I can understand the complaint about pricing changes on BA. As I understand things, BA (and other European airlines) use quite a different pricing model/strategy from US carriers so this is one area they don't match their offering.