I agree. I imagine the hold up is testing/certifying that a new system doesn't cause issues. Modern LCD screens in seat backs seem to suffer from fuzzy video ... providing a digital connection for both audio and video seems an obvious solution. I know providing a screen for every passenger sucks more power but LED TVs (and potentially OLEDS) are reasonably power efficient.
I flew Easyjet last month ... they took credit cards and, more importantly, cash in pretty much any currency (their terminals could do the conversion). It was great for getting rid of random currency and, in exchange, they got to sell me overpriced coffee!
I've read a couple of research papers on the matter but they tend to be inconclusive. I've read that the unassigned seating system works reasonably well (people just sit down rather than hunting for a seat ... probably why the LCCs use it).

Whatever, this is a great list and I certainly identified with quite a few of these ^.