but the cost of a new set of brakes is astronomical when compared to the fuel usage during moderate reverse thrust usage
That
may be so but studies carried out by at least one large airline indicate that the cost of more frequent engine hot end maintenance (due to additional heat cycles generated through use of reverse) easily offsets the cost of brake usage. Also if you have carbon brakes the extra wear for the additional braking effort is negligible.
To an extent I also agree with Captjns' tongue in cheek comment
The function of Thrust Reversers on the CFM equipped 737 is to make lots of noise and consume fuel.
.
If runway length and/or braking effectiveness is in doubt then of course use up to full reverse. However 3000 meters of dry runway and I sometimes see folk apply full reverse down to 60 kts - the pax don't like it and nor do the beancounters.
Regards
Exeng