Hey, thanks a lot for playing and sticking around with us for so long!
To clarify on your proposal, the game would work like this: Player has an "inventory" of parts which can either have parts stored or grown. If part gets killed it becomes lost. So player doesn't have a universal resource to grow new parts, but parts themselves be a resource.
We've thought about this before and it's a pretty neat and hardcore idea. It would enforce "roguelikeness" of the game, but work against player being able to choose what to grow, as it would only be able to grow what's left in inventory. So it's roguelikeness vs creative freedom. I think Such gameplay would encourage "safe play" in which player tries to minimize the risk. We are already punishing player for losing Zooids, but we preserve the creation which automatically re-grows once there is enough nutrition. If game worked by proposed rules, we couldn't preserve player's Sipho design. One game I know that works similar way is Captain Forever. I personally felt reluctant to engage in fights that may result in losses as then I wouldn't be able to easily redesign my ship back to the way it was.
It could work as a separate game mode we could consider adding after release and I'll make a note of it. Thanks!