Spell-reading not only teaches how to read, it provides a tool for integrating the tajweed rules into the same process -- i.e. how to read with tajweed altogether. So, there is no need to first learn how to read Arabic, and then go back again and learn how to read Arabic with proper tajweed. Further, using the spell-reading tool eliminates the problem of "guessing" when reading from the Mushaf (Qur'an).
Even after the Noorani Qai'dah program has been completed and the student is reading from the Mushaf, he or she will come across a difficult or unfamiliar word or phrase, especially in the beginning. At that point, if the spell-reading tool has been mastered, it can still be used with confidence to figure out how to accurately read - with tajweed - any word or phrase in the Mushaf.