Interesting article.
It seems to be its a circle of co-dependence: the various charities can benefit from a royal patronage, and the royal family existence relies heavily on public appearances at events which both keep public approval and maintain public interest.
As a tax payer, and a visual learner, I like to SEE the money alloted to the senior royals' salaries spent on them making appearances, and supporting causes that I believe in. I agree that the scale and impact of royal patronages has increased dramatically- particularly within the recent climate of the growing favour for a republic in various commonwealth nations (and in Britain)- and the politcal importance of the patronages adds another dimension.