Grammar and spelling are things that develop over time to a certain degree in living languages, so one shouldn't be too precious about these matters.  Certain words and phrases, never mind spellings, that were in use a couple of hundred years ago are no longer in use today.  That said, a piece of writing that is badly-spelled or punctuated grates on the eye.  

Someone passed me a letter recently that contained the phrases "you was wrong" and "you should of".  Much of this sort of thing may be attributed to laziness or poor education.  There are some words that are often misused: most people say "can" when they should say "may", but that is what happens in a living language.

I think that English-English has more elephant traps than American-English.  For example, when to use the word "practice" instead of "practise".  I sometimes think that American-English uses spellings that are slightly more logical than English-English, but please don't ask me to say "chips" for "crisps" and "fries" for "chips".  

Chips iz chips and crisps iz crisps.  Nuff said.