In Jean-Francois Lyotard's critical opinion of postmodernism, metanarratives (also known as the "grand narratives of living") are problematic because many of these narratives, particularly the ones presented in Don DeLillo's postmodernist novel White Noise, do not clearly point out the nature for legitimation. In simpler terms, we do not know exactly the nature of Jack's neurosis with death, nor can we see him as a tragic hero who is suffering unjustly by his fears despite his want to change for the better. We cannot even analyze Jack under the scope of a potential philosopher who digs deep into his daily events to make something out of it. What we have is a narrative that goes in and out of the main character's consciousness, showing the frailty of the character's connection to his real world, and to his true nature. The narrative is constantly interrupted by mundane and illogical blurts of what your question dubs as "routine dailies", many in the form of commercial breaks showing everyday hygiene products. Other daily routines brought up in the narrative seem to bring unnecesary information heard in the whereabouts of the house:
Some of the other people were in the kitchen preparing the meal, some had
gone upstairs to investigate their gifts in private. The TV said: "This
creature has developed a complicated stomach in keeping with its leafy
"I don't like this business with mother," Bee said in a voice of cultivated distress.
The way in which the narrative is so spasmodic, and coming in and out of the consciousness of the main character (without much concern to him) results in what Lyotard would call "the loss of faith". This entails the absolute deflation of the purpose of the main character due to a society where consumerism has eaten the very core of his sensibility. This loss of faith is basically the nostalgic emotion that the reader feels when realizing that Jack's entire life (as well as the narrative of the novel) has been driven by his fears. He will not redeem himself; he will not be better. Yes, "it is that bad" in a consumerist society, and there is no hope for us as a race. That is where the loss of faith aspect hits the idea behind a postmodern metanarrative.
Evidence of this comes right when we are about to see a change in Jack's life; the moment when the supposed Apocalypse is coming and he is forced to face his fears. As we prepare for Jack's ultimate challenge (facing death) and we almost take his side in wishing him the best.... we get an anti-climax in that the event never happens. Jack is asked to "go home", and the Gladneys basically continue their old habits and customs.
Hence, a great narrative does not always preclude that it will tell a great story. It does not prescribe for a great event to be told, nor does it guarantee that there will be a redeeming factor taking place. In this case, the reader loses the faith when it no longer can connect with a character that does very little to connect with his own reality.