The basic design problem for Balance, as I know you know, comes down to Wrath and Starfire just being very similar spells. One is always going to win out by virtue of damage or cast time. Eclipse was our attempt to make which one wins more dynamic. I think it accomplishes that, but I think it's also fair to say that there aren't a ton of druids who are in love with the talent. Or maybe it's more fair to say that there are druids who just can't stand it. It's also not swell that the talent has driven many druids to mods to help manage it.
I'm one of those druids who picked up a mod for Eclipse, not because I'm a mod enthusiast, but because I felt it was mandatory in order to maximize my dps. It would have been a disservice to my raid to not pick it up. There's a 30 second internal cooldown to Eclipse and since the game does not tell the player when that cooldown is over or about to be over, the best thing to do is pick up a mod that will track it.
This prevents the player from accidentally proccing the wrong Eclipse and also lets them maximize their dps by pumping out their nuke of choice (whichever they have the idol for) without fear during the cooldown phase.
But the fact that a mod is so useful, perhaps even necessary, for maximizing the dps granted by a single talent is wrong, and it's good to see that Ghostcrawler realizes this. He was extremely vocal about pushing Eclipse on moonkin as a way to make gameplay more dynamic for us, but I really don't see that. I'm still nuking. I'm still refreshing my dots. The only difference is that I now watch a few bars winding down on a mod I didn't have before and I follow a couple of new rules I picked up that only exist because of Eclipse (i.e. don't refresh dots during an Eclipse, or if you do, only right at the beginning). I'm using both nukes in a single battle, which is admittedly different, but dynamic?
I have no control over Eclipse, and due to its random nature it can proc at times I can't even take advantage of it.
I actually rather enjoyed what I experienced in Burning Crusade, where the rotation used changed based on gear, idols, and possibly how the raid itself was composed. There was the low mana consuming rotation (IS/SF), the medium mana rotation (IS/MF/SF), high mana rotation (IS/MF/W) that you could potentially use in Kara and ZA. Then there was the MF/SF rotation in T5/T6 gear, and finally SF spam in Sunwell (which I never saw).
I liked changing my rotation as my gear changed, because it felt like progression. But my rotation in Ulduar isn't any different from the way it was in Naxx.
Ghostcrawler says that the problem comes down to Wrath and Starfire being too similar, but the reason I changed between the two back in my ZA days was to manage my mana pool (a problem that is sadly no longer an issue). If I knew I had the mana I used Wrath (higher dps, but higher mana cost), and if I didn't I used Starfire (more mana efficient). If mana was still an issue, then the difference between using Wrath and Starfire could again be a real choice for moonkin, where what the player used could actually change from fight to fight based on how long the moonkin suspected the fight would last and how much it would take out of them.
Instead all a moonkin does now is spec into a few regen talents (which used to be mandatory!) as necessary to make sure they don't run dry. It may be an important thing to do from a talent perspective, but it doesn't require on-the-fly judgment in a boss fight itself.
I remember changing my rotation mid-fight, going to a Wrath rotation to burn down a boss because I had the mana, or going to Starfire to conserve myself.
It just doesn't happen anymore and I think that makes being a moonkin more boring than a lack of an Eclipse.