First of all, you're pure evil if you make a kid play Amnesia
(I'm actually thinking of gifting it to my friend who thinks that The Passion of the Christ and Bioshock are scary
)
Secondly, as much as I'd love a hard copy (day 1 buy for me) you have to consider FG's position, making boxes and cds is very expensive and could actually cost them money seeing as so many people have already bought the game.
However, keep buying Frictional's games and I'm sure, once they become a bit more successful, that we'll have a "Frictional Boxset" featuring the 3 Penumbra games, Amnesia and the game they're working on at the moment (which, just between us, my 6th sense is telling me will be awesome).