Picard as well as Kirk make a different decision than Soran. Although they are very happy with their private lives in the Nexus they yearn to do something more important with their lives. This is one of the oldest stories of humankind, Gilgamesh builds a wall around Uruk when he realizes that he cannot become immortal.
You cheat death, you become immortal not via living forever but via doing something great that creates the illusion for you that you live eternally via this great deed.
You can also phrase it differently, Soran is basically already a zombie, he has nothing but the drive to live whereas Picard and Kirk have the desire to fill their lives with something significant.
Sure, all of this is not perfectly done in GEN but you cannot just wipe the ideas away. For a Trek movie it is thematically pretty rich.