Safeguarding a constitution against retrogressive amendments is of paramount importance for otherwise:

This has led some to argue for an unamendable constitution. Attractive as it may appear at first sight, it overlooks the crucial fact that however rigorous the procedure for its making, a constitution may still contain imperfections or become outdated. As George Washington himself noted in 1787: ‘The warmest friends and the best supporters the [United States] Constitution has do not contend that it is free from imperfections; but they found them unavoidable and are sensible that if evil is likely to arise there from, the remedy must come hereafter.’ Further, as Justice Khanna of the Indian Supreme Court has noted, no generation has a monopoly on knowledge that entitles it to bind future generations irreversibly, and a constitution that denies people the right of amendment invites attempts at extra-legal revolutionary change. In short, ‘a constitution that will not bend will break’.

Further we must not forget that an unscrupulous executive may seek to make a constitution unamendable for its own political ends. For example, the Constitution of Ghana 1979 came into effect following the handover of power by the Armed Forces Revolutionary Council to a civilian government.