@apathetec; you're missing the point. It's not about the one MP. That one MP doesn't make the laws, the 650 MPs as a whole make the laws at Westminster. Their views are a more important and more distinct different than geography.
I can twist the issue in the other direction: in a FPTP system, only about 40-something percent of the people are represented, it's only in safe seats where the number of people who want that candidate is greater than those who don't want them.
But in a PR system representing the whole country, every major party gets a seat, so unless someone is supporting a very, very small party (that's most likely either redundant or extremist), they're getting represented! So instead of a 40% chance, it's more like a 99% chance of representation.
Of course, I'm twisting the issue myself, but I trust you get the picture.
I hate how a party with 36.9% of the vote gets about 50% of MPs while a party with 12.6% of the vote gets a small fraction of a percentage of the seats. Most of you hate UKIP and will thus write that off, so I'll give you this: the Green Party gets 3.8% of the vote and also just a small fraction of a percentage of seats. Even the Lib Dems got screwed: 7.9% of the vote but only a bit over a percentage of the seats.
Does the FPTP system have advantages? Yes. Does the PR system have flaws? Yes, but some of those are negated by a mixed member system, as in Germany. I think that the benefits are more important, of representing different people's different views.
In the US, we have two views. What are they? Ask me and it's statists with red ties and statists with blue ties. Ask a liberal (i.e. most people on the internet) and it's conservatives with red ties and conservatives with blue ties. Ask a conservative (i.e. most people here in the non-urban south) and it's liberals with red ties and liberals with blue ties. What we all can agree on is that very few of them represent us, the people. A more PR-ish system can have more views represented, and that would be a great thing, don't you think?