There are several Buddhist philosophical and folk traditions, each containing its own set of assumptions, values and cosmological underpinnings.
One particular tradition is the Zen Buddhist tradition. Zen Buddhism values mindfulness in everyday life. Meditation and contemplation can help a person cultivate mindfulness. In the Zen Buddhist tradition, enlightenment comes through sudden insight. After enlightenment, a person continues to engage the everyday world. Enlightenment doesn't mean that person knows anything more, but rather that their perspective has fundamentally changed.
In the Zen philosophical tradition it is said that "samsara is nirvana," or "wandering is enlightenment." This means that an enlightened person continues to search, seek, and wander. In fact, seeking, searching and wandering are integral parts of enlightenment.
Thus, a person who has everything and knows nothing of sickness and death would not be satisfied. Part of being satisfied is having something to struggle with, having something to contemplate deeply, and knowing nothing of sickness and death takes that part of the human experience away.