Why does Jesus eat with sinners?

Mark 2:15 And it came to pass, that, as Jesus sat at meat in his house, many publicans and sinners sat also together with Jesus and his disciples: for there were many, and they followed him. Matt 9:10 And it came to pass, as Jesus sat at meat in the house, behold, many publicans and sinners came and sat down with him and his disciples. Luke 5:29 And Levi made him a great feast in his own house [1]: and there was a great company of publicans and of others that sat down with them.
Mark 2:16 And when the scribes and Pharisees saw him eat with publicans and sinners, they said unto his disciples, How is it that he eateth and drinketh with publicans and sinners? Matt 9:11 And when the Pharisees saw it, they said unto his disciples, Why eateth your Master with publicans and sinners? Luke 5:30 But their scribes and Pharisees murmured against his disciples, saying, Why do ye eat and drink with publicans and sinners?
Mark 2:17 When Jesus heard it, he saith unto them, They that are whole have no need of the physician, but they that are sick: I came not to call the righteous [2], but sinners to repentance. Matt 9:12 But when Jesus heard that, he said unto them, They that be whole need not a physician, but they that are sick. 13 But go ye and learn what that meaneth, I will have mercy, and not sacrifice: for I am not come to call the righteous, but sinners to repentance. Luke 5:31 And Jesus answering said unto them, They that are whole need not a physician; but they that are sick. 32 I came not to call the righteous, but sinners to repentance.

[1]It is not clear how Levi could make a "great feast in his own house" when he "left all" in Luke 5:28 (Interpreter's One-Volume Commentary, p. 682).

[2]This is the only place in the gospels where Mark and Luke quote Jesus as referring to "the righteous." In Matthew, Jesus refers to "the righteous" on four other occasions (13:43, 23:29, 25:37, 25:46). In John, Jesus does not use this phrase at all.