lot of these writing tasks can be done at various levels of proficiency and can be fairly short and informal. Others may require that letter layout techniques and formalities be taught first and are more formal. A lot of them are creative, require some imagination and are fun to do.
ESL writing skills are as important as reading, speaking and listening skills. Knowing how to write in English can make the difference between settling down in an English-speaking country and flitting through as a tourist.