English is one of the few European languages that doesn’t have a ‘Language Academy’, which stipulates which words can and can’t be used, spelling norms etc. This has the effect of freezing a language in time and can make it sound archaic. English does take words from many languages and does not have the constraints of an academy, but this is different to basic spelling and grammar to some extent, as the meaning can be completely different i.e. ‘Your’ and ’You’re (You are)'. Creative writing is brilliant, but even stuff like this will be checked by someone at some point to ensure the majority of people can understand what is being said/meant. Regional variations/accents/dialects is another matter and sometimes they can be used to emphasise differences rather than similarities or ‘rules’.
The ‘overt’ Americanisation of British English is annoying, but probably inevitable, but while I have a breath in my body I will continue to keep a ‘u’ in colour and flavour and a ‘y’ in tyre etc.