Yes, it's about control, and desire, and the inability to really satisfy either. Not only do kids have to adapt to their parents' needs and requirements most of the time, but even when they are offered a desired toy or activity, they don't necessarily have the motor or language skills, or simple experience, to make the most of it. Or they are already in emotional overload, and can't readjust when they actually get a choice.
Consequently, toddlers often lead mind-bogglingly frustrated little lives. A process called Emotion Coaching is effective. Toddlers will still be toddlers, and sometimes they just have to rage. They will have little impulse control for a few more years. But to the degree you can empathize and help them name their frustrations and unmet needs, they begin to realize you genuinely care about their predicament. That can be almost magically calming and supportive.
Dr. Harvey Karp, author of The Happiest Toddler on the Block, models one type of emotion coaching here: http://www.youtube.com/watch?v=fJ1428uYs2g&NR=1&f...
There's also a very fine book that helps parents understand how to emapthize with their children's emotional needs: Raising an Emotionally Intelligent Child by John Gottman. Children whose parents practice "emotion coaching," as a group, are more physically healthy and emotionally resilient, less affected by stress, perform better academically, have better relationships, and are less likely to develop behavior problems.
You probably already pay attention to this, but kids will do best when they are rested enough, not hungry, and not overstimulated/rushed. Some kids are also extremely sensitive to household chemicals and/or food additives, which can trigger mood swings or sleep difficulties in addition to physical problems.
