It was not until the water actually started to rise around him that he went into the ark. By sending out the dove, even though he had no intention of going out of the ark until Hashem commanded him, Noach was doing teshuva. He was returning to Hashem, fixing his previous lack of faith. By sending out the dove, Noach was demonstrating that even though he had the possibility to rely on natural indications, he would act only on the word of Hashem. The Midrash tells us that when Noach was late in bringing the lion's food one day, it turned around and bit him.
Nothing happens by coincidence.
If it was the lion that bit Noach, it must be that Noach had transgressed and that the lion was the fitting agent of Noach's punishment. The first Beis Hamikdash actively protected the Jewish People, whereas the second Beis Hamikdash awakened people to repentance, but didn't actively protect them. They would actively protect us. Noach, however, was criticized for not praying on behalf of his generation. He built the ark.