Alright m8?
Leaving aside the truly horrible way language is descending into SMS-speak ("c u l8r", and so on), I just hate, hate the way totally unknown people use over-friendly words. It's just about bearable when a more elderly lady calls you 'lovey', perhaps in a shop when she serves you, but when another man who I don't know and who most certainly isn't a friend calls me 'mate', I just want to shout 'I'm not your mate!' The dictionary says that a 'mate' is a friend or partner and I abhor the word being used for no reason at all.
Comments
It's the evolution of language. Language will evolve it has done since the first words were spoken, and will continue to do so. Whilst there are grammatical rules that are followed to bring coherence in words, the words themselves will evolve. Meanings will change, words will take on new definitions. I'll give one example, from hundreds. Gay. What it meant once, it does not anymore.
You are living through a technological revolution and language is evolving and reflecting those changes. Communication technology is bringing down barriers between people and the formalities of yesteryear no longer apply. I honestly don't mind people I don't know calling me 'mate'. I view it as a term of openness and friendliness on their part. We may not know each other but the other person is introducing the conversation on a personal, low intimate level. No formalities required.
I certainly prefer it to the style you get in Italian, where you have one language for your friends and a totally different language for people you don't know. I will never get used to shop keepers addressing me in the polite form, no matter how many times I go to Italy. For once, English has an advantage in it's informality that makes conversing on an open level with people you don't know so much easier with the friendly open level language often used.