I have no idea what harvesting gene-seed would do in the game or if it really needs to do anything, but I'd like to see it happen any way.
Presumably an Apothecary can 'harvest' them via a kneeling animation, and the player gets revived. The Apothecary can only do this so often (skill based) and players can only be revived so many times. Perhaps there's a limit on the skill (IE five 'harvests') The Apothecary can harvest (revive players) and then has to fall back to restock the skill or cooldown? (lore wise, can be explained in that the apothecary is getting more vials of preservative solution)
More infantry requisition (to use planetside 2 terminology)? I don't know how I feel about medics 'reviving' fallen comrades in a game that has excecutions, but I certainly think that it would be cool if they could harvest the corpses to add to some... global requisition pool (or even chapter based if we want to be really lore accurate) that would allow more troop deployments and better equipped troops. Or at a stretch, you could even just allow it to provide the apothecary and the fallen marine a small amount of XP.
It could just be a perk for the Apothecary (and all healeresque classes), a way for them to earn more requisition. I'm not super keen on the whole revive thing, but if it is done then I don't think that players who have been executed should be able to be revived.
To be honest, if I could harvest organs, I would. Make moneyz on the black market yo! ...I guess you could get some resources out of this. Not that much point to implementing it though.
Still voting for a reduced respawn time for those that have their geneseed extracted. It is after all extracted from corpses to be reused in new recruits. It can be completely unrelated to the reviving mechanic.
And what's the point in harvesting the gene-seed in a videogame? reducing the respawn cooldown? you realize the other faction will need a similar mechanic?