Witchend
The read loads until secondary is common. I'm not convinced that shift is because in one subject for 3-4 hours a week they study texts that aren't perfectly what they'd read for pleasure.
Primary reading is done very differently. Equally, more parents read with their child in primary (either because they see it as a thing to do with your child or because the school has reading records etc). By secondary very few parents read with their child.
Equally, how many parents who wish their child read more sit down on an evening and read a book? Talk to their children about books? Take them to the library? Ask them what they'd like to read? I'm sure some on this thread will, but it's not the norm.
On parents evening we get loads of parents saying "I wish they'd read more... How do I get them to read more... It's like they've suddenly turned into a pre teen and are more concerned with social media, their phone, console etc than reading".
The purpose of English lessons isn't just to read books that might be fun and that students would probably read anyway.
JamieVardysHavingAParty I agree with you. Teaching comedy when getting the comedy requires a whole wider set of knowledge and experience is really dull.
The other thing is that it's exposing students to books and styles they wouldn't normally consider. I have a love-hate relationship with Of Mice and Men but year on year students love it.
Personally, I wouldn't want to teach Harry Potter because whilst there's some interesting ideas, there's a lot to be said for letting children have their literature for their own pleasure and enjoyment rather than pulling it apart for language analysis.
Howlongtillbedtime
Thank you. Book choices is a bit of a personal interest of mine. I probably need to get out a bit more. 
Honestly, I do see what you mean about some different themes, but when you're probably studying 1 novel a year, 2 max to cover poetry, plays, non fiction, speaking and listening, creative writing, grammar etc that's not really a huge amount of time to cover everything. So a class novel night be sad, but then the poetry could be poetry about place, or love poetry. I'm yet to have worked in, or with, any English department who do nothing but depressing death themes lesson after lesson. They may exist, but usually texts are chosen for their complexity and range of ideas and usually they are explored.
In my experience, unless there is a fundamental literacy barrier to accessing a text, most texts can be taught to most abilities and made accessible.
I really do believe that if students are having an experience of English that's an empty feeling of sadness and doing nothing but talk about deaths be suicide then that's not a text issue, it's a teaching issue.