On Simchat Torah we read Vezot Haberachah in conclusion of the annual Torah-reading cycle. It is the day of rejoicing the Torah, but not of receiving it.
In breaking the tablets, Moses was acting on his own, contrary to his divine mission to deliver G-d’s Torah to the world. In breaking the tablets, Moses, who could not presume that G-d was to replace the first tablets with a second pair, was eradicating his very being, his very raison d’etre, for the sake of his people.