Fr O'Callaghan makes many good points, but seems to have overlooked others.
I am thinking of considerations such as:- space for burials plots; and the consequences of charges made for grave leases.
As he says, burial in a given place, with name and date, and a marker such as a cross: These things allow the deceased person to be remembered. And yes, they give a "powerful message of concreteness, of the particular person who has died".
However, in European countries such as Italy (with which I am familiar), Catholic cemeteries charge for burial plots; and significantly the payment needs to be renewed every 50 years or so. If no-one makes the repeat payment, the body is removed (and it does not seem to be done in a very "sacred" way).
His claim that "burial is more ecological than cremation" seems to overlook the point that burial places in some places are now very limited. Also overlooks the fuel used in (say) creating funeral stones and monuments.
But he does seem open to options. Good.