Most vegans know to take B12 supplements, but there are other hormones and stuff you only get from animal products.
That would be part of the 'more planning' in dropping all animal products. There's also the work to make sure there's adequate protein, and enough calories. Though the raw food movement might be where there's the worry in getting enough calories.
Anyway, millions of people are happy in the middle ground. Less processed and prepackaged foods. More fruits, vegetables and legumes, smaller or fewer servings of meat. It's healthier than the typical American diet, without requiring a lot of study, extra supplements, monitoring and prep.
And, yes. I did just call myself lazy.