I’ve read all the posts in the thread (I think) and I would like to add my two cents (or maybe pennies?) in the conversation.
To begin with, the mutation of a language is one thing, the misuse of a language is another.
In regards of mutation:
1. A language is a live thing and it changes through the ages. As time passes it will evolve to cover the contemporary communication needs and as a result new words will appear and older words might be forgotten.
2. English is still quite a primitive language and it will go through many changes, more than other older languages at least.
3. The Americans, being a population of people with many different linguistic backgrounds, are trying to rationalise the relationship between pronunciation and spelling. For example meter/metre, theater/theatre. These words are pronounced the same both in US and Britain but the British still keep the Greek spelling.
4. Since the American English are more widespread through the movies, TV series etc. some of the changes they carry will inevitably prevail which isn’t necessarily a bad thing.
In regards of misuse:
The main issue when people are not able to use correctly their native language is lack of reading.
And when I say reading I mean books or well written essays in news papers or magazines and not posts in the social media. Unfortunately according to a recent article of The Guardian one in five children in the UK doesn’t own a book.
This results to people who are just trying to reproduce a sound as they've heard it, which is not always correct, without having seen it written on paper. Hence I hear many people saying drawring (drawing), sawring (sawing), free (three), brought (bought), let alone what happens when they are trying to write something.
Reading good books will not only make you appreciate the beauty of a language, but it will also improve your own way to use the language and you will be less vulnerable to the linguistic absurdities that are widespread through the internet. Books will expand your knowledge as well, broaden your mind and enhance your critical thinking, but this a topic for a different thread.