As adventure level goes up, far too many sites appear on the map that have no function at all.  That is, when I step on them, they do nothing even when my adventure tech is sufficient.  I suspect that the quest that they fire has already been completed, so there is nothing for them to do.  So... there they sit... forlornly awaiting a visit from a champion.

Quests should be world unique.  That is, only one site should spawn them.  This gives an advantage to the player with the best adventure tech.  Said another way, players that wish to invest in having the best adventure tech should get the first crack at the best sites.  That said, there should be lots more quests... as I am sure the modding community will be happy to fill the need.