There is perhaps another risk of FPTP in modern politics that hasn't been mentioned yet. Realistically, for a long time to come yet the only two parties with a chance of winning an overall majority are Labour and the Conservatives. This will be true right down until the parties are picking up 30% of the total vote each, perhaps even a couple of points lower still. This would mean that there is no need for the two parties to appeal to any more than their core voters, because that would probably be enough to secure the necessary vote share (plus, possibly, the tactical voters who would rather see one side in than the other without truly supporting either of them). The result could be even more polarised politics, as the two main parties move further from the centre and towards the wings.
Perhaps for the next few years this might not be a bad thing as the two parties are often said to be rather too similar to each other; but in the long run it makes for a fouler mood in which the middle ground gets ignored. I don't see how that's healthy either. This sort of thing wasn't really a problem under a two- or even three-party FPTP system, when the vote share needed for victory was something like (core voters + 10% of total electorate).
FPTP just doesn't make sense any more. It obviously would not have affected the result, but I might well come to regret voting "no" in the AV referendum.