Allow me to explain. Some of us were raised in a time where an English teacher would whack our knuckles with a ruler if we answered incorrectly or were not paying attention. Beatings in hallways with wooden paddles with holes drilled in them to raise blisters on one's backside were also used. Basically, teachers were Nazis and your self-esteem didn't mean jack. There were no points for just showing up, You had to MEMORIZE what you learned well enough to pass a test at the end of the year, not merely a few hours or days later. FAILURE was a bad thing and if you WERE one, other kids would mock you for being an idiot and that was practically encouraged.
Therefore, Grammar became REALLY damn important for your well-being. Many of us who had to endure that took it to heart and passed the attitude down to our kids.
And it really IS important. Accurate communication is the foundation of good relationships with other people. If you say or write the wrong thing, you can easily cause confusion and misfortune for others. People could misinterpret what you say, become offended and punch you in the face and entire wars could be started over a typo in certain cultures. If we don't get serious about education and grammar, each generation will become dumber and lazier about it. Ever see the movie "Idiocracy"? It's supposed to be a comedy, but the premise of the movie is actually happening and it should scare the crap out of you.