Slogan-making is a tricky enterprise, and there are many opportunities for it to go awry. African-American Lives Matter, for example, is clumsy for shouting, and its adoption would have been a big mistake. The conciseness of Black Lives Matter is a real plus. Better, not much longer, and without any words longer than two syllables, is Black Lives Matter, Too. This delivers exactly the right message, especially to the white population: not only do white lives matter, but black lives also matter.
Alas, an opportunity was missed.