Except Louis XVI was neither weak-willed or indecisive, although he was arguably naive. He tried to reform taxes and remove the noble privileges, but all his attempts were blocked by the regional parlements.
Hence why Necker convenes an Assembly of Notables in 1782. He learns from Maupeou's mistake in that staging a bureaucratic coup against the
parlements will not work, so decides to circumvent them. The Assembly is handpicked to consist mostly of partisans of Montmorin and Necker, and their job is basically to rubberstamp Necker's reform plan. I am sure that even if they were to agree to implement his plan, there still would be significant opposition. But potentially Necker could use the famine (as well as the threat of war over the Netherlands in ~1785-87) to justify the radical reforms.