Far from a waste, I would consider this miles well spent. Transtalantic J class is very very expensive, and the use of miles gives you the one great bonus - room, and on red eyes, a chance of some peace and quiet. it will, if you fly American allow you to go through Fast Track on arrival, and it allows you again with American (maybe the others have other rules) to use the lounges which makes waiting for the flight all that more pleasant.

This is quite apart from the enhanced service and service levels abord the aircraft which are , of course, another bouns.

Enjoy your trip!