The HSC English (Advanced) course, in my opinion, is a more of a literature-based course rather than a language-based course. Obviously, those who appreciate the world of literature would enjoy the course more than others with critical and analytical thinking involved.
Whilst in any text we analyse the features of the language being used and how these convey meaning, a primary focus in the HSC English (Advanced) course is the way social, historical, cultural and/or political contexts can shape the way meaning is depicted in a text. The reason that this course has little emphasis on language effectiveness is probably because students are expected to have exhibited mastery the english language to at least a satisfactory extent by the time they have completed their School Certificate (though this is not true for many cases).
However, the English (Standard) course has more emphasis on language effectiveness than the English (Advanced) course probably because students in the English (Standard) course may need more work on how to improve their language skills. Therefore, the many complaints about the jargon riddled English (Advanced) course [which even many teachers complain about, as indicated by a detailed support document found under the online syllabus] by many people could perhaps be a case of the wrong course of choice. If you prefer to study language effectiveness, then perhaps English (Standard) would be more suitable for you. However, if you prefer to study literature in various contexts, then perhaps English (Advanced) would be suitable for you.
The english language is not static, it develops over time. The high frequency of colloquial and next to vulgar language is likely to be a result of youth expansion and freedom as well as (of course) the power of media. It can be said that older generations are trying to keep the value of the older and more formal form of the english language alive and by the time you age, chances are that you'll do the same. The HSC English course (surprise...surprise the BOS is run by older people!...lol) can be said to also try to encourage the preservation in the value of the old english language before the next generation drives it to extinction. Therefore, we are encouraged to appreciate this form of language and preservation of this old english language is the most likely purpose of having compulsory study of Shakespearean plays. Obviously, due to the way that we are shaped by a modern context, this study may prove to be pointless and tedious to some since it does not correspond to our common modern language.
On a side note, something that I had found out recently:
Unfortunately there is an assumption made in this course when it was developed, which I think is a flaw for both English (Advanced) and English (Standard). One aspect of the course which is supposedly an effective way for students to "enjoy" the course is the aspect of related material. The course assumes that all students are reading widely and have had exposure to many texts under various concepts relating to each module. It is believed that students will find the course more enjoyable with flexible access to various related materials which they supposedly enjoy to help them in the understanding the concepts in the course. The incorporation of prescribed texts and related material is believed to be an effective way of managing the course.
Although this ideal appears to be an effective mechanism of the course, in reality a large number of students do NOT read widely or take part in literature actively. Most students often spend more time enjoying the advances of technology and entertainment rather than read widely. I'm sure many would rather be blown away by physical sound effects of a concert or movie than picture it in your imagination. Arguably, it may encourage students to take part in literature in search of appropriate support material in order to meet the requirements of the course, but it is often obvious that once students have found their related material, chances are that many of them do not look any further and do not dig deeper into the wide world of literature.