The reason for "doing this sort of thing ie talking about him endlessly" is because the people and government of the USA decided to go back to executing people.

The result is that attention is focussed on the killing ritual, and undoubtedly, for some people, this is an element in bringing them to commit the crimes that end in this public killing. Timothy McVeigh was/is probably such a person.

There are strong ground for believing that the overall effect of capital punishment in a country is not to deter murder, but to encourage it. That would seem to be borne out if you compare the murder rate in countries which have the death penalty and countries which have abolished it.