I have recently been thinking a lot about which is more important for second language learners: pronunciation or grammar. I have also spoken about this to some of my colleagues – most of which are Japanese and have 10+ years experience with the board of education teaching foreign languages.
Whilst most had different ideas about the specific details, all of them agreed that pronunciation was not only more important than grammar, but the most important thing in second language acquisition. Period.
Simply put, because if your pronunciation is bad people will not understand what you are saying or trying to say. This in turn will also result in people being less inclined to want to talk to you.
Some people can get away with using more simple vocabulary or more simple sentence structures, however there is no way around this when it comes to pronunciation. You can not use simple pronunciation. Your pronunciation is either good, where people will be able to understand what your saying, or bad, where people will not be able to understand what your saying.
I think that this is part of the reason why such emphasis is put on teaching phonics to children. You want them to learn the sounds of the words and the correct pronunciation, before even thinking about how it is written. That all comes later.
Smith’s School of English, for example, seems to understand this and thus focus the emphasis on the conversational aspect of English. I think that this is a very good thing.