Re: We don't vote for parties...
or from the article: "In one sense, no. We get the government we vote for."
Because you don't. Locally maybe, but on a national level the local-representative election system the UK uses will heavily skew the seat distribution on even minor differences in voting totals. Because the local winner takes all, and only needs a marginal victory to take that victory, the system ensures that a "majority" national government representation will always be an actual minority by votes.
Because the difference needs only be so small locally, it's also very hard to accurately poll for or model outcome, unless you have limited (bi-partisan) options and/or a very conservative voter base that's not likely to switch, because you cannot use national totals to predict the outcome for a single constituency. Which as far as I can tell happened here more than pollsters getting Wrong Answers. They simply applied the data wrong.
The system in place in the UK works fine for a bi- or tripartisan setup, but this election was typical for having five major players, each with their own major issues and programs. And that's where things went wrong, because anyone who's done any system analysis can see the the "dilution" of votes would mean that massive amounts of voters would basically get shafted, as their representations in votes would never stand a chance of being materialised in the house of commons.
The worst hit, and potentially the most dangerous artefact of this, is UKIP, who did get a fair share of the vote, but lost out in the dance-of-chairs. Like them or not, it is terribly dangerous to ignore a set of sentiments that, by votes and by distribution, is a serious nationwide affair that now has no representation in government, and as such no release valve. Even if UKIP does not survive this, the sentiments will not disappear and it will bite peeps in the back the next few years.