Tests of Faith

Hizkiyahu's prayer in the face of a prophecy from Yishayahu of his impending death and the reversal of this prophecy to extend his life and his reign for 15 more years makes Hizkiyahu a paragon of faith. Conversely his dealings with Berodakh Baladan, King of Babylon, are criticized harshly by Yishyahu. Divrei Hayamim paints a picture of arrogance and pride as leading to Hizkiyahu's illness and perhaps the censure he received for his dealings with the Babylonian King. Melakhim seems to be critical of putting faith in other nations and forming alliances as a rejection of faith in God. 

These two stories lead to a broader discussion within Hizkiyahu's character and in general of proactiveness versus faith in God. The Sages criticize Hizkiyahu for chanelling the waters of Gihon into the city and for utilizing the Book of Remedies as expressing a lack of faith. Are these criticisms justified?