Why do we have 247 letters in tamil?
That's because we can always make sure a letter is always that letter alone.
A ka is always a KA - not Ga or kaa as it could be otherwise used in other languages.
The intent here is to spread the rich heritage of Thamizh without a tinge of change in its luxury to the maximum extent possible. Intend to teach this ancient language that speaks of its people and culture and more of its richness itself vividly. As we teach, socialize, learn, grow, let us enjoy the fun.