It's about the Bill of Rights

The changes introduced in the electoral system are a consequence of the framework that the Bill of Rights has sought to establish. In other words, without the guarantees contained in the Bill of Rights, it is of null effect to provision for democratic electoral processes, and utterly hopeless to attempt to implement such systems. Excerpts from Chapter 4 - The Bill of Rights, Part 2 - Rights and Fundamental Freedoms, Article 38, excerpts:

38. (1) Every citizen is free to make political choices, which includes the right— (a) to form, or participate in forming, a political party; (b) to participate in the activities of, or recruit members for, a political party; or (c) to campaign for a political party or cause.
(2) Every citizen has the right to free, fair and regular elections based on universal suffrage and the free expression of the will of the electors for— (a) any elective public body or office established under this Constitution; or (b) any office of any political party of which the citizen is a member.
(3) Every adult citizen has the right, without unreasonable restrictions— (a) to be registered as a voter; (b) to vote by secret ballot in any election or referendum; and (c) to be a candidate for public office, or office within a political party of which the citizen is a member and, if elected, to hold office.