The reason that 'it is as it is' is because of the requirement to be a silver or gold member and because it takes ages to manually connect each manual to a product, let alone do it twice!
The reason some manuals are included in multi product manuals is because that is how B&O made them! The speakers are a classic example with a couple of manuals dedicated to various ranges.
On the making it difficult to download, clearly this is not the case as the majority of manuals for sale on eBay have been taken from here. I now do add some security to make life a bit more difficult but I dare say this just slows the thieves down. Quite why the Beogram 3000 Acoustical is always listed on eBay is beyond me. I only know of a couple of these and both owners are Gold members!!