In a child's book made into a full length movie, I expect plot events to be, you know, added. (Think, Polar Express, etc.) Here, it's just the events from the very short book, spread over time mixed with sleeping in a pile, throwing dirt, and many violent and petty arguments.
Some have said it's all metaphorical, that each wild thing represents parts of Max or his family. However, I don't believe we know enough about his family to make any informed connections. We only see them at the very beginning, centered mostly around truly disturbing behavior in Max. Honestly, he needs evaluation and probably medication. Max looks to be about age 10 or 11, and my 3-year-old would be in trouble for behaving as immaturely as he does.
So, if you are in a Child Psych 101 class, analyze it in your thesis paper, include which wild thing is who and why...knock yourself out. However, as a movie experience: dark, depressing, and so boring, even the mother character falls asleep at the end.