Here's why:
* Cuneiform was a syllabic writing system, meaning each symbol could represent a syllable (like "ba", "da", "ka"). This means you had to remember a lot of symbols and their associated sounds. The symbols were also complex, made up of wedge-shaped marks pressed into clay tablets.
* Phoenician was an alphabetic writing system, meaning each symbol represented a single consonant sound. This made it much easier to learn, as you only had to memorize 22 symbols. Plus, Phoenician script was written from right to left, much like modern languages, making it familiar to us.
While both scripts played important roles in history, the Phoenician alphabet proved much more efficient and adaptable, eventually evolving into many of the writing systems we use today, including the Latin alphabet used for English.