Absolutely true, the cost of a certificate extends beyong simply copying the contents of the register, for a start the storage and archiving of the millions of records has a cost. It isn't that long ago that certificates were considerably more than £7.
I find it quite amusing to see comments against the expense of certificates but see people who willingly purchase and spend large sums of money on credits to view the 1911 census.
If everyone stopped ordering certificates today would the cost of archiving change. I think not. Information is gathered by an act of Parliament, we the public pay for it wether we order a certificate or not.