We may finally know of a contributor to players' thoughts that Cataclysm heroics are too difficult. It looks like your luck hasn't actually been with you so far, as Luck of the Draw has been broken since the expansion's release.
Ghostcrawler posted an update today to reveal that they've fixed it in patch 4.0.6, and they're also making a change to its functionality. Now you'll gain a scaling buff for each random player in your group, up to a cap.
Previously the buff increased damage, healing and health by 5% so long as you had one random player in the group. As of the patch, it's going to scale for each random player in your group, up to a cap of 15%.
"Cataclysm dungeons, especially on Heroic mode, are quite challenging and ask for more group organization than the Wrath of the Lich King dungeons did," Ghostcrawler wrote in the blog entry. "Therefore, Luck of the Draw became relatively weaker in Cataclysm."
The mindset behind buffing Luck of the Draw, rather than further nerfing bosses in the dungeons, is that it will make the lives of pick-up groups easier, while still retaining the challenge for those organized groups that don't have to utilize the Dungeon Finder to fill out their group.