In an ideal world, you would imagine that a democratic country would be best administered by a centrist party that attempted to walk the line between extremes of opinion, and that tries to please the majority of the people the majority of the time.
Thinking about it, and observing what is happening in western countries at the moment, I am inclined to disagree for the following reasons.
What is the centre ground? The centre ground is whatever the media says it is, on any given day. Witness the continued circling of Miliband by most newspapers...They slated him endlessly for not admitting that cuts were necessary and relevant, then when he finally says as much, he is now a flip flop politician afraid to defend his turf. Ditto Cameron, he will bend to public opinion and then be slated for doing u-turns. Surely it is the job of politicians to listen to advice and public opinion and respond to it?
Thus if the media decide they hate HS2, then any politician who backs it, is out of touch and away from the centre. Replace HS2 with anything really. Likewise, if the media suddenly decide that slamming shut the doors to EU immigration is flavour of the month, if you oppose that as a politician, you're shafted because the centre has shifted at the whim of the media.
Natural left wing people are not partial to right wing 'methodology'...Ditto the right is none too pleased with the left's 'way of doing things'. I will refrain from saying goals because often, when you dig into what left and right wingers want, it's often the same thing...They just disagree vastly on how to get to those goals.
So politicians who attempt to walk the centre line will just end up pissing off both the left and right equally, because both sides will feel that that politician is crossing too far over to the other side for them. I have seen some eminently successful ideas shot down in flames simply because neither side wants it, they see it as an alien idea to them, despite it trying simply to please all the people all the time (see Abraham Lincoln on that quote).
So why walk the centre ground? Set out your stall and stick to it...Surely it is better to have one side of the debate want to push you off a cliff, if the other side would be happy to follow you over it?