My FC regularly does 8-man runs for treasure hunting, with each of those 8 players having multiple maps stashed away. It sometimes takes an hour or so to clear them but we make several hundred thousand gil towards our FC housing fund each time we do this.

The real key here is to ensure you always do them with 8 people as the gil rewards are static so more gil is generated if more people join.

If you play solo a lot or don't have a FC I can see why some would be disappointed with treasure hunting but our FC really loves it so far!