Like everyone here has already said, you are the only person who can decide what is fun for you. If it's feeling stale, just change what you do on a daily basis. I see lots of forum posts about people missing the "good ole days" of learning the fights without watching a video and making lasting friends in game because of the bond you get from trying and failing over and over and then finally getting that win. If you like dungeons/coil but are getting sick of just going in repeating the same old steps, try going as a different class. Or even better, take on a mentor role for a new player/start a new static with people who haven't done coil to help teach them.

At the end of the day none of us get anything for playing the game, just like every other video game. There is no tangible reward, but for me, the friends you make while playing are the reward (I'm still friends with the core group of people I played FF11).