Is simplicity inherent or a person can become simple by practice is the big question...really there are several people who are at times very simple and down to earth in nature, but at times they show different shades in there life... one thing is for sure that nobody is good or bad, everybody has grey shades in their life.
Even god some times shows different shades, just for example if we see lord Rama, he ate fruit which where given to him by a woman named Shabri who belonged to lower caste. This instance gives a very liberal shade to his personality and preaches his followers to never consider anybody lower to you, treat everybody with equality, on the other hand there is another instance in his life when he asks his wife Devi Sita to give Agni Pariksha and further leaves his wife into forest just because someone said somethings about her...how complicated it is, we are able to see different shades in the personality of Lord Rama.
Lord Kirshna also is a great example of simplicity. He had friend circle belonging different classes.He use to play with them, eat with them, enjoy with them which gave an innocent shade to his personality but see he was the person who was able to make a plan of action against Guru Dronacharya.His planning during Kaurav Pandav war was impeccable which show he had a very deep knowlegde of war tactics and the diplomacy. Then he himself coming out with Bhagvad Geeta and explaining it to Arjuna, every thing is very impressive about his personality.