Perhaps this IS the accepted behaviour for the cathedral - and always has been?
Anyone who has read historical books on the cathedral will know that things were even more irreverent and chaotic in the middle ages! In the 15th c, Jerónimo Munzer from Nuremberg described the goings on and hubbub in the cathedral as so great that “he would have believed himself at a fair.”
The cathedral was a loud, noisy place, with pilgrims from different nations fighting and squabbling to position themselves close to the altar, singing and dancing to their musical instruments.
Walter Starkie writes about the golden age of the pilgrimage when there were all night vigils in the cathedral and thousands of pilgrims regularly waged battles inside the cathedral - sometimes so severe that blood was spilled and the cathedral had to be re-consecrated.
Early accounts of the cathedral refer to pilgrims lighting fires and cooking food in the cathedral and even bivouacking inside with their cows and horses!
Some reports describe “conducted tours of loutish pilgrims tramping in serried crowds through the basilica, tripping over the kneeling penitents outside the confessionals.” And while this crowd pushed and butted their way around the cathedral, the congregation tried to follow the celebrant of the mass at the high altar.
It seems that cheering and clapping is certainly not new and we, of the 21st century can’t really describe it as a “drop in standards” or a ‘decay in values’ when those standards and values have always been there.