Its primary effect (and, ultimately, only effect) was not to raise revenue, but to suppress private currency.
I do not see how that can necessarily be concluded. This seems to have been but an excise on private currency, no different than any other excise.
This tax was imposed by a general revenue act. It levied taxes on "many hundreds products of the country" (to use the Supreme Court's words from
In Re Henderson's Distilled Spirits). From the context, it should be very clear that this is a revenue measure, not a regulatory one. For a court to strike it down without absolutely clear evidence would be to overstep the bounds of the judiciary.