It has been said, that the intention of Dilithium was to be the currency that rewards people for playing the game.
This vision has clearly been lost in the transition from paper to game, because in its current form on tribble, I'm not seeing it.
At my current level, (Federation Lieutenant Commander 1) there are three ways to collect Dilithium.
The first path is PvP, this path is blocked currently.
This maybe resolved when the game goes F2P and has a surge in population, for now there is rarely anyone in queue.
The second, is foundry missions.
This is probably the best path if you desire a quality game-play experience that is rewarded with Dilithium.
However the best foundry missions take a long time to complete and thus playing though three of them for the modest 1440 Dilithium Ore you get, is just not efficient.
Lastly, and I cringe as I write this... Explore missions... This is truly the *** end of the game.
And though some people can have a blast running around, destroying 10 ships, scanning 5 rocks and so forth I myself, steer clear of the grind when possible.
However, this probably remains, the most efficient way to earn Dilithium.
Honestly, I'm unimpressed and I suggest, that you return to your original concept.
You've got this great Ore refinement system, that allows you to regulate how much Dilithium people can earn per day, my suggestion is simple: USE IT!
Why not give people Dilithium ore, regardless of how they like to play the game?
Why not give Dilithium ore to people who play though the story progression?
The quality of STO's PvE progression has consistently improved since launch and I feel that this is probably you're greatest strength, so how about you pass me some ore after I finish “The Doomsday Device” and keep me where you shine the brightest?
Why not give Dilithium ore to people who play Fleet actions?
Perhaps you could give out slightly more to people who work well as a team, be they healers, tanks or DPS.
This may have the added bonus of encouraging people to join fleets for this purpose.
Active fleets are the heart of your community and whenever possible you should make it as desirable as possible to be in one.
(That said I am not currently in a fleet.)
Why not give Dilithium ore to people who play Patrol missions?
These missions are usually grouped into at least three actions per mission, much like explore missions. They can be painstaking long and at times tedious and grindy.
I'm still playing your game though, and whenever I take one of these assignments or turn it in, my mouse hovers passed that cute C-store button that seems to have crept into the UI. :p
Why not give Dilithium ore to people who grinds Signal contacts?
I realize grinding has to be carefully regulated, and I'm not a big fan of grinding myself.
However, it is still time spend playing your game.
So how about it Cryptic?
This is your big chance to re-launch the game and draw in a larger audience than ever before.
If you want to keep them however, you may want to focus on directing people toward the games strengths, instead of highlighting it's weaknesses.