This is a culture difference. I as a Brit absolutely detest when sales staff are pushy and forcing their way into your purchase decisions. This is generally highly frowned upon in UK culture and is not something the majority like.
I do however agree on some of your other points, such as poor selection and useless staff.
I prefer if they don't approach me unless I'm obviously looking for help, but in my cases shopping in the UK it was "there is nothing useful on the shelf, I need to find out if there is a product by asking an employee" and not being able to readily get one.
I do however agree on some of your other points, such as poor selection and useless staff.