I would think that if everyone was immortal then everything would be slowed down. To me death is a motivation to live my life to the potential, if this was taken away from me I would probably be on my couch playing games rather than studying and developing into the person who I am now. Also, if you lived for eternity wouldn't live become dull? You would have travelled around the globe, maybe even into space, but in the end what will you do to entertain yourself? As my favourite television character (The Doctor) said "You make all of space and time your backyard and what do you have? A backyard."