I will try to keep this rant within acceptable limits (only 200-300 pages).....
Literacy is paramount; it is vital. We are an increasingly technologically advanced species, with all that implies; this includes, among other things, increased rate of communication (that is, the speed with which something that happens in one part of the world is known to another, not an increase in the accuracy -- and therein lies the rub). Because of this, there are increased tensions, cultural diversities, differing points of view (due to level of education -- many countries have simply appalling literacy levels that make the U.S. look like Utopia, god help us; not to mention cultural/political bias against any facts that oppose the current regime's or the overall cultural agenda), etc., etc., all of which are exacerbated to a terrible degree by lack of clear communication, which relies entirely on just the sort of grammatical and punctuational points we're addressing here. Not to mention that science and mathematics rely on precision of language, and errors in grammar can change the entire understanding of vital points in these. A good example is to take even such a "simple" thing as the Lorenz-Fitzgerald contraction equation. Now, alter a single term within that equation. As a result of that one tiny change, the equation either becomes complete nonsense or gives results that completely changes our understanding of astrophysics. The same is true of more "common" languages, including English. Joyce proved this in a very in-your-face manner with Finnegan's Wake, which hinges on the placement of a single comma. Now, this is a rather longish novel, and the understanding of the entire thing relies on that one comma; Joyce proved this by leaving out that one tiny little mark on paper, causing that to be one of the more difficult novels in the entirety of English/Irish literature.
"Great oaks from small acorns grow" is one way to look at it; perhaps a more fitting, if grimmer, is the "For want of a nail the horse was lost..." (And, I suppose, since most people I know have never even heard that one these days -- another indication of how our education both at home and at school is eradicating our links with the past as well as botching those with each other-- I'd best give the entire thing: "For want of a nail, the horse was lost; for want of the horse, the rider was lost; for want of the rider, the battle was lost; for want of the battle, the war was lost; for want of the war, the kingdom was lost -- all for the want of a horse-shoe nail."
And we have historical examples: as Latin began to decay, so decayed the Roman Empire. While it was not simply a correllation of corruption of the first ending with fragmentation of the second, it was a large contributing factor, as it meant that differing parts of the empire simply couldn't communicate efficiently with each other, and lack of that communication meant that vital actions weren't taken, and the fragmentation spread. And so it goes....
Language as a communication tool is fragile at best; put too much strain on it, and soon we truly do end up with a Tower of Babel, where people think they're being intelligible, but the person hearing them gets an entirely different message; increase in misunderstanding ends up in increase in violence, apathy, loss of cohesiveness within a culture, etc.
Anent the lowering of standards: Lovecraft, in one of his letters (I don't have them handy at the moment, so I'll be (mis)quoting from memory) used the analogy of those who were in the skyscrapers being at a higher level than those on the ground, and in a truly democratic society this became a very wicked thing; and so to build up the level of those on the ground, they began to tear down those skyscrapers. And in the end, they found that the ground really wasn't any higher, and they'd lost all their lovely towers. If we dumb things down, we all lose; there are inequalities in the system, but these have to be addressed by raising the requirements for teachers and for administrators, and resistance to political action groups that don't want certain things taught because it conflicts with their worldview. If, for example, in science, one thing has the weight of evidence behind it, and the opposing view has little or no verifiable evidence, one is simply speculation; the other is science. The idea becomes a little harder to explain in English (or the equivalent language), but it still applies, though the explanation has to be longer and more complex; but there are certain standards that are simply better than others, and this can be demonstrated; the fact that our educators (and our politicians) cannot do this, with the materials to do so ready to hand, is sickening -- to me, literally; I feel a sinking in my gut when I contemplate this.
And, yes, we are becoming lazier. This is something we can change but, being primates particularly prone to procrastination and laziness, we are unlikely to do so. On this one, as on so may of my Cassandra-style predictions, I'd dearly love to be proven wrong. So far, this has not happened.
I repeat: Literacy is paramount. It is vital. Not only to our production of a worthwhile culture but, in the end, quite possibly to our very survival.