Michael
Commercially if the whole magazine could easly be downloaded by a digital subscriber in one go in a universal format, then inevitably someone somewhere will then forward it to all and sundry (or try to sell it) resulting in a net loss of sales, either digital or printed copies.
So, yes it can only be downloaded page by page, which is intended as a deterrent to this happening. The resultant poor quality will also be a factor in preventing 'free' distribution.
Digital editons are intended to be read online and perhaps a selected article to be downloaded and later printed by the digital subscriber themself, hence the price reduction reflecting the cost saving in not printing and distributing a copy of the magazine. That is why the Free Plans are not included in digital subscriptions, because otherwise they might become truly universally 'free'.
All of this is pretty much standard across the industry.
Paul Freshney
Editor.