The purpose behind Eclipse was to encourage Balance druids to cast something besides their hardest hitting spell over and over again. From this thread it appears at least some of you were content with a "rotation" like that, but you'll have to believe me that it was a very common complaint we heard from druids as to what they disliked or why they didn't play Balance.
Now it's possible to base a rotation around a single spells. Mages are designed to do just that. However, they also have a lot of procs, cooldowns, secondary effects and other situational events that mean that even though you're getting most of your damage from one button, you're managing a lot.
We could have gone that way with Balance druids. We didn't largely because part of the kit of Balance is balance, and we thought that manifested itself nicely in switching between Arcane and Nature spells, or Starfire and Wrath, or Lunar and Solar.
The problem with Eclipse (as I've stated many times, so I find the comments that we won't address the issue to be a trifle unfair) is that it now accounts for so much of Balance's damage that the random element can be punishing. Having to shift positions right when you get a proc should be a little bit of a bummer on the level of missing a few crits in a row, and not a devastating blow to your dps.
We're keeping Eclipse, but the Cataclysm version is a pretty radical overhaul that we hope to be able to reveal soon. It removes a lot of the random element. :)