Because in a war of attrition you're never going to win if you are wasting resources like this. It's an act of desperation and the Japanese knew it, that's why they did it. The very name, Kamikaze refers back to an unwinnable situation where the Divine Wind (not a man-made action, mind) saved Japan from the Mongol fleet. Yes, for Japanese it's understandable because of their culture, but changing the balance of power and swinging the war in Japan's favour? Next to impossible.
Precisely why it's not a good idea. As for the effectiveness, it's a bee with one sting, a bomber can be recovered and retasked, a Kamikaze can't, even if he fails in his objective. Next to the successes, I'd like to see the failure rate too, those shot down and those who missed their targets and died trying. I wouldn't know where to look or whether such a thing has been collated.
The concept is revered with almost mythical status in Japan today, with museums around the country, notably the Yasukuni Shrine, but also the Chiran Peace Museum near Kagoshima (the last surviving Ki-84 is there) paying homage to it, which is spiritually comforting for those who lost loved ones. But an effective deployable tactic that's gonna reverse the outcome? Not at all.