Why are there no Standards for Baggage Sizes

Why oh why is there no standard for the sizes of bags you can carry onto aircraft?

Oh there is in theory and there are baggage manufacturers who build capacious bags to those exact dimensions but they have failed to take into account the penny pinching mentality of the low cost no frills carriers who think its is both fun and profitable to reduce the sizes of bags that can be accommodated on board their own aircraft.

I am not talking here of Ryan Air who think that a carrier bag from Waitrose is too big to carry without a surcharge.  No I am talking about the Flybe's and the easyJets of this world who when they construct there rules shave just a centimeter off here and there off the official specifications just so they can catch the customer out and charge an extra charge.

Virgin Atlantic - Way behind BA

Let me say at the outset that I am no great fan of British Airways in fact I believe they have a huge amount to learn from the likes of the newly emerging Gulf State carriers but they are good enough for what they do. 

Yet to read the advertisements and listen to the bragging of Virgin Atlantic and you would assume they consider themselves to be light years ahead of their rivals in the skies, British Airways

Not so, in fact quite the opposite.   Cramped seats smaller, than BA, that are not only narrower but have less leg room, seem to be the normal.

The selling of emergency exit seats and bulkhead seats at an extra premium is another sign that Virgin would like to follow the Ryan Air school of customer abuse if they thought they could get away with it.

I remember so well the gusto with which Sir Richard launched this new airline saying it was going to change the world of flying.

So years later with Virgin just another airline and a poor one at that I am forced to ask the question; What went wrong?