Triple Play Blu-Rays - worth the money?

[benfrankcave]

Since recieving my blu-ray player at christmas and being a real fan of special editions i have been purchasing the triple play editions so i can play them at my folks house who have not yet converted to blu-ray but also so i can have the digital for my iphone/ipod as well as the blu-ray itself. However i have just found out that the digital copy expires! The activation code may expire within a given time and then the digital copy may be totally useless. I realise that most wouldn't be too bothered by this but i'm in a situation where my computer is dying rapidly and i can't really afford to buy a new one so i may, in the case of one of my Blu-rays Transformers 2: Revenge of the Fallen, not manage to get the copy onto my/a computer before it expires. It expires November this year! I kind of feel i've paid for the digital copy as much as the blu-ray and should have it permanently to transfer to my pc or mac when i chose!
I'd love to know opinions, i may just be being a little strange or possesive. also why it was decided that the digital copy has an expiry date.