I chucked away all my boxed copies of Frontier and FFE years ago when I had stopped playing them, and whilst I had them I never looked at the contents much as I remember. And you can pick up old Forntier games for next to nothing now so they wont go up in value, just down.
So it comes down to personal preference, mine is that the paper stuff will just take up valuable space in my house so I am getting digital only. I considered getting books, artwork and all that at one point but tbh I will never look at it more than once, and all I am bothered about is getting the game. Perhaps if I had a massive house with loads of storage I might be tempted to get a box, but I can always do that later on and for a lot cheaper than they are available right now.
So as a practical person I eventually got the minimum I could get away with (ie the game) and will get everything later after the game has come out on Ebay if I feel the need then. But of course that was when you got access to the Founders World, Commanders Name and 500 credits etc. I wouldnt buy the game now because you dont get anything other than the game. I would wait until the game comes out and buy it then as it will be a lot cheaper, unless you feel the absolute need to gain access to the alpha or beta stages, or to support Frontier's development costs.