Doing just one per day will make you a contributor to your realm's progress and increase the rate at which you unlock new areas. The final area unlocks the Nalak world boss so if you're eager for more loot from him that's a reason to invest a few minutes each day finishing one daily quest. Otherwise the only incentive is the VP and the gold. If you're not interested in those then there's no reason to do them.
Ritual Stones and extra Troves keys basically. It's also nice of you to do just one to help build participatimn.
If you aren't raiding Normals at a consistent rate, doing the Ritual Stone quest once a week nets you 150 Valor, along with additional Shado-Pan Assault rep. The Key's are a nice bonus too, but not really mandatory if you're only interested in epic loots and gearing up.
Though keep in mind that the Dailies offer something around 60 VP for a full completion, which is the equivilent of running an additional Heroic and Scenario, so if you're looking to max your VP gain per week without raiding, doing a Heroic, Scenario, and the Dailies will earn you VP the quickest if you're not doing Challenge Modes or Raids. The Rare also always drop a Tome of Valor worth 15 VP, so there's another small bonus as well.
Each person might see a rose with a different shade of red, but the fact that we can all agree on is beauty -- that is a miracle. -Michea, FFXI