Cricket3: I agree with your other hand... I actually think you're showing exactly WHY it's important to really teach grammer, not just to pay lip service. Grammar is deadly boring and often incomprehensible if you do it wrong, but quite powerful if you do it right.
Now, we might be going a little over the top... my english speaking 3 yr old knows what case is

But we've been teaching it the way we teach socially appropriate behavior. If he says "I is going" I often, but not always, reply "you should say I AM going, becaue 'am' is the second person of 'to be'" So it's just the explaination part of the usual gentle correction for errors.
As an adult, I have taught myself grammar mainly by creating little useful creoles... adding latin endings to english words so that I can decline them and similar. Despite having a decidedly better than average understanding of grammar, I feel strongly that my lack of grammar skills limits me from accomplishing many of my goals. (Including looking like a competent human being on the internet!) I just don't have as much controle over the medium of language as I feel I need.
The big three things I feel my education as a child really dropped the ball on are, history, geography, and basic language/math skills like grammar and calculation)
Oh! and there's that bit about how the generation that are kids now are likely to spend considerably MORE time than their parents communicating in written form, and are likely to use a wider range of moods in their written communication, making it more necessary to clearly differentiate texting from thesis writing

My usual 203 cents, sorry. I tend to be opinionated.