Men naturally have hard hearts. Why you think God provides a new heart in it's stead? Ezk 36:26The Bible says that people are responsible for the hardness of their own hearts:
8 And the word of the Lord came unto Zechariah, saying,
9 Thus speaketh the Lord of hosts, saying, Execute true judgment, and shew mercy and compassions every man to his brother:
10 And oppress not the widow, nor the fatherless, the stranger, nor the poor; and let none of you imagine evil against his brother in your heart.
11 But they refused to hearken, and pulled away the shoulder, and stopped their ears, that they should not hear.
12 Yea, they made their hearts as an adamant stone, lest they should hear the law, and the words which the Lord of hosts hath sent in his spirit by the former prophets: therefore came a great wrath from the Lord of hosts.
13 Therefore it is come to pass, that as he [God] cried, and they would not hear; so they cried, and I [God] would not hear, saith the Lord of hosts:
14 But I scattered them with a whirlwind among all the nations whom they knew not. Thus the land was desolate after them, that no man passed through nor returned: for they laid the pleasant land desolate.
A new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh.