"Are these remakes a sad reflection on the caliber of writers available today or simply the result of greed for some easy money?"

Perhaps we should never see another production of Shakespeare?

It is not a sad relection on the writers - if anything,the better remakes are probably more difficult for the writer than the original.   The writer is trying to find something new in order to "sell" the film to a new audience.   I think "Ocean's 11" took a mediocre film and turned it into a wonderful franchise.