It's only "cultural" in that Europe has a long-standing culture of wealthy people building huge memorials to their dead, and yesssss the "nouveau riche" (i.e. people that other rich people don't quite approve of having as much money as them) are probably a little more guilty of this than others.
It's not "cultural" for travellers specifically, or for Irish people. Everyone does it - has always done it.
Even in ancient Rome we know of people from non-culturally-mainstream backgrounds building slightly eye-popping grave memorials to themselves before they'd even died, just to be sure they were fabulous enough, and many of the super OTT memorials we get all sentimental about at Père Lachaise Cemetery, or Highbury, or Laeken in Brussels probably raised some eyebrows when they went up first.
The music and the lights are probably a step too far, but I don't see any problem with the general excess. It's their family plot, and they have built a large grave on it in a very recognisably European Christian style.