The King has an increased income indeed but he has also lots of extra costs as well. In the book 'Aan het Hof' by Meijer and Hoedeman was written that Queen Beatrix pays around two dozen of the most close and trusted advisors and functionaries out of the "private" component of the State Allowance. Think about the private treasurer, the re-imbursement of the non-paid Hofdames and Chamberlains, parts of the program on April 29th, 30th and May 1st which were paid privately, etc.
Since there is more transparency in the finances of the Royal House, the functional costs are fully accountable for public scrutiny. So I think when stripped to the core private part of the State Allowance, it is not thát much more than the (already very generous) private allowance the King already enjoyed as Prince of Orange.