Well, in literacy classes in the UK learners are definitely taught phonemic awareness as part of their learning. I can't speak for other countries, however. In one sense, I can see the value in adult learners being taught phonemic awareness. Research has shown that increasing a learner's phonemic awareness in turn helps them to learn to read and write more quickly, of if there are adults who can't read and write and struggle with it, working to develop their phonemic awareness is one strategy to help them learn the vital skill of literacy.
However, arguments against this view would point to the exclusive focus in the phonics system of learning to read and write on phonemes alone. The massive problem with the English language is that we use so many words that have no correlation in terms of the way they are written with the phonemes that they contain. So, for example, a word like "ought" or even "caught" sounds completely different from the way it is written. Teaching a phonics-based system might have the impact of just confusing adult learners. Some research is emerging that suggests the level of spelling is decreasing because of the adoption of a phonics-based system in schools.
Absolutely. As a teacher who has been trained in a structured reading program, and as a professional with a Master's Degree in Special Education, the importance of phomenic awareness skills has been reiterated time and time again.
Humans learn how to read based on their ability to hear and manipulate phonemes. And, as you may know, phonemes are a set of speech sounds in any given language that serve to distinguish one word from another. Without the ability to recognize such sounds, one is unable to distinguish words from each other. A person may be able to learn how to read sight words without relying on phonemes, but as words increase in complexity, it is essential to understand sound letters in order to be able to read these multisyllabic words.
So, while the task of teaching phonemic awareness can be difficult, especially when teaching adult learners who must be taught the foundational skills of phonemes, this is the foundation that will allow an adult to read with fluency and accuracy. The ability to decode words is the basis for all reading, and includes the abiltiy to comprehend what we are reading. If even one word is not read and understood, the entire meaning of that sentence can be lost.