Literate or Illiterate...Is that how you say it?

Literacy, literate, illiterate...mah. Why isn't it unliterate instead of illiterate? Ill reminds me of sickness...certainly that can't be right. This is the point. I don't think we can ever distinguish a line between the literate and the illiterate but if I had to draw a line I would say it in regards of communication; between whether or not I can understand what they are trying to tell me. If someone is literate, I can tell what they are trying to communicate to me. If they are "ill"literate, I have no clue what they are trying to convey to me. For example..someone who says the word "unliterate"...I would understand what they are trying to tell me. But if someone say "bobfinkitoo"...ummmm need I say more? I believe English can be taken to literate. It can be taken too seriously. We talked the other day about how who/whom is being lost:  I completely agree but do I care? Not really. As long as my students understand English, grammar, and are able to communicate effectively, isn't that the point? Isn't that enough? Maybe it is, but perhaps it isn't.