I hate writing! How does anyone ever learn to do it well?
Just because some writers seem to make writing look easy, doesn't mean it is. Writing is a lot like running--it stinks until you are conditioned well enough to enjoy it. If you practice writing as faithfully you practice basketball, eventually, your writing will look like the equivalent of a three-pointer.
Why should I read Shakespeare? It's not even written in modern English.
Actually, Shakespeare is written in modern English. It should be read and enjoyed because it's entertaining and shows the universality of human existence. Sex, murder, incest, greed, and jealousy are not just part of today's world. Shakespeare was aware of all human foibles and weaknesses and presented them brilliantly in his plays
Why does it matter if I use correct grammar? Isn't it enough that I'm making my point?
The way you respond is a direct reflection of you as an individual. It tells others more about you than your shiny hair or perfect nails. It tells the listener that you have cared enough to learn the proper use of your native language. It could be the difference between you and someone else being hired for that dream job.