I have heard an explanation for this state of affairs from ex-politicians and from political commentators who seem to know what they are talking about.
The media these days is labouring under the misapprehension that the news is just another form of entertainment. Consequently they are not interested in publishing or broadcasting sensible explanations of policy, but prefer witty one liners and mindless slogans, preferable two or three word, alliterative slogans.
It is probably a bit of a chicken and egg situation, but it is a waste of time for a politician to give a sensible explanation to the media, because the media won't publish it. They think the public need to be entertained rather than informed. So politicians have learned that the only utterance likely to be used by the media is a short sentence or slogan that tells us nothing, but sounds good.
Politicians have been reduced to playing a game forced on them by the media. You could argue that they should rise above that, but I can't see it happening while the media are convinced, rightly or wrongly, that the majority of the population have the attention span of a goldfish.
When you combine that with the emphasis the media, some politicians and some members of the public place on opinion polls, it is no wonder that we don't get long term planning, commitment to sensible policies and informed debate.

