Why should we care so much that one Labour MP - one of 257 - has decided he does not want to represent the people of his constituency any more?
We care because this is no ordinary MP.
You may not have heard much about David Miliband recently (that has been a deliberate approach on his part) but this is the 'nearly man' of British politics.
He nearly became Prime Minister, but decided not to challenge Gordon Brown for the top job when Labour was in government.
He nearly became the leader of the Labour Party after the election that Gordon Brown lost, but his younger brother narrowly beat him to it.
He came close to the top job, but he has now turned his back on politics - and on Britain too.
There are many in the Labour Party who still think they would be in a stronger position - and have a better chance of winning the 2015 general election - if the older brother had won the leadership contest.
But David Miliband concluded that he could not play a major part in the party while his brother was at the helm.
Every speech, every policy announcement, every interview would be picked over for signs of disagreement with his brother or policy differences.
It would play into what former Cabinet member Tessa Jowell already described this morning as the "legitimate fascination" with the fraternal melodrama.
There are also those who were clinging to the fading hope that David Miliband would lead them in the future, if Ed loses the next election perhaps.
But Miliband senior, the man Alastair Campbell nicknamed "Brains", is taking his brain to the USA. There is never really a place at the top for the man who previously came second.
Inevitably, the assertion will be made that David's decision is a verdict on Ed Miliband's leadership and the way Ed is taking the party away from the Blairite agenda.
But David Miliband has clearly decided in the last few months that his political career was going no further.
He has already held one of the great offices of State - he would play no further part at the top of the Labour Party - so the only option left is to step off the stage.