Tony Benn sits in a carved medieval-style wooden chair that once belonged to the pioneering socialist MP Keir Hardie. This is just one of the symbolic objects that surround him, as selected by Benn himself, in a portrait painted in 1998 by Andrew Tift for the parliamentary art collection. There's a vial of Benn's blood in the painting, just to show that it is red and not blue: it alludes to the fact that in 1963, Benn renounced a hereditary peerage so he could run for election to the House of Commons.

By 1964 he was postmaster general in Harold Wilson's first government, yet he was to move further and further to the left while serving in Wilson's cabinets. Another object in the painting shows exactly how far left, for on the shelf behind him sits a bust of Karl Marx. He plants himself in that chair chewing his trademark pipe and wearing, of course, a red tie, with his head among the Marxists but his rump firmly in the democratic tradition.

Portrait of Tony Benn by Andrew Tift. Photograph: Palace of Westminster

A likable visual record of one of the most striking lives in modern political history, you may think. But no. According to just about every news outlet this is part of a collection of "vanity portraits" paid for by taxpayers' money at the whim of a cross-party committee of MPs – and the latest scandal to alienate the public from Britain's political class.

Nothing reveals the current sickness of British democracy quite so acutely as this universal condemnation of a respectable art collection. I can think of art expenditures by parliament that might be genuinely scandalous. If MPs spent a million quid on a gold statue of Kate Moss by Marc Quinn to decorate the House of Commons tea room, I'd be shocked. If they gave Damien Hirst 5 million to cover Big Ben with dots, that would seem excessive. But is it actually at all extravagant that – over a period going back to the 1990s – a total of £250,000 has been spent on not one work, but an entire collection of portraits that add up to a serious visual record of the outstanding MPs of our time?

All the MPs chosen for this honour are memorable for their achievements or their personality and public voice, from Diane Abbott to Ken Clarke. When I saw these portraits recently at Portcullis House, I was impressed that MPs had the imagination to create such a sustained archive of modern history. Only a nation that utterly loathes its own elected representatives, and by implication its entire system of government, could find something to attack in this serious collection, that puts Abbott's face into history alongside the portraits and statues of her white male Victorian parliamentary predecessors. Painted portraits still flourish as a way of honouring someone and acknowledging their place in history. The National Portrait Gallery adds to its collection all the time – why not complain about its regular royal commissions, which come from public funds just as surely as anything parliament commissions?

I have not filed a freedom of information request on this but I am pretty damn sure it costs a lot more than £250,000 every year to maintain that architectural behemoth, the Palace of Westminster. This old gothic folly must cost endless millions to constantly restore, and what about the heat and lighting? On the logic of the TaxPayers' Alliance, which finds it so disgusting that some high-achieving MPs are commemorated by portraits, we should sell it off. Let MPs meet in an underground car park.

But I am wasting my breath – apparently we British really do hate our MPs that much. The portraits "scandal" shows how irrational this hatred has become. This is a democracy. To hate our elected representatives is to hate ourselves – isn't that obvious? Parliament has seen some genuine scandals in recent times, but it also has a massively honourable history. A civil war was fought to establish that kings must listen to it. Winston Churchill spoke in it. Just last year, a project to bomb Syria was defeated by it. Surely, the fact that MPs foiled the military ambitions not just of David Cameron but also of the US in Syria ought to give pause to those who preach empty nihilism about the British democratic process.

Those who dismiss MPs as nothing but corrupt charlatans are in serious danger of rejecting democracy itself, which has never existed in some platonic ideal form but always, everywhere, in the kind of flawed human fabric of which the House of Commons is so richly made up. Painted portraits of living MPs are a decent and reasonable way to document the latest chapters in this ancient institution's long story. Tony Benn, and yes, Diane Abbott, Ken Clarke and Tony Blair, have all earned a place in the history of British democracy – and they deserve their portraits.