I thought you were going to answer the question, but you decided to answer the How, not the Why, as the OP asked. So I'll give it a shot.
It has to do with the intention of a separation of powers. Having a president who appoints judges and requiring 2/3rds of the senators to concur, was a compromise in writing the Constitution. Some the framers of the Constitution did not want a powerful President, having broken away from England and King George during the Revolutionary War. Others like Hamilton are said to have wanted a monarchy, rather than this experimental representative government.
A chief executive was certainly needed, but the Constitution was designed to hamstring the president, which is why Congress was designed to have a critical role. Washington and Adams pretty much played by the set rules.
But Jefferson, who pushed in the Constitution for that weak president, went off script when he got elected to that office. He created the Executive Order, when he thought it necessary to create a navy to counter England's aggression. Congress was against it, or at least Jefferson feared they'd turn him down. From then on presidents have used executive orders to go around Congress, when deemed necessary. If the framers wanted the president to have all this power, there would never have been a requirement for the senate to approve judicial appointments.