I readily accept that some people who travel a lot for work, do not want more free flights but many of us do! Many of us have family and school friends a long way away.
Some carriers allow you to use the FFMs to buy gifts from their catalogue but better value is gained from giving them as presents to your relatives. I have known children being able to fly across the globe to see grandparents for the last time, as the older person could not sustain the flight themselves.
As with Slim, I have used my miles to upgrade family on long haul as a present and next year will be helping my mother to do the same when going to South Africa to see family. It may be her last trip there and she needs the flat bed and I shall use more points to upgrade myself to Upper,
so that I can accompany her. From my point of view, that is worth the collecting.
If you do not want the miles and the (sometimes dubious) benefits of FFM schemes then try to avoid using airlines that operate them. Alternatively all carriers enable you to donate unwanted miles to charity programmes to buy seats for terminally ill children to go to Disneyland and so on.