The fiction which gives legitimacy to our government is that the process of having elections every five years disciplines MPs to act in the general interest. Whatever comes out of Parliament is the "result of the democratic process".
The significance of Ann and Alan Keen counting ten thousand a year of what is basically an investment as an expense, and getting it signed off as such, is not in the cost itself - the hundred million a year or so that MPs take for themselves is a small part of their impact - it is that this conclusively disproves the legitimacy theory.
If, as the theory holds, MPs are constrained to act in the public interest, then everything they officially do must be in the public interest. Pocketing an extra ten grand a year, effectively in cash, is not in the public interest. Therefore the MPs are not so constrained. Q.E.D.
As a corollary, there is no reason to believe that anything else they do is in the public interest either.
via Devil's Kitchen