An Egalitarian Obligatory Contribution

Yoash suggests that funds be collected for the Temple through the priests. Why does he think this is the best way, and why does the system later change, and the money collected in a box directly in the Temple? The system is reminiscent to the Half Shekel contribution, and the anonymity enables a degree of equality in the nation's participation in the Temple. This prevents donors to contribute only in order to enhance their social status.