When I started this thread I made an argument about food as a game mechanic, but people still derail it into "pops need food because that's what they eat". So why don't we have to manage water supply supply, then? It is also essential, but we don't have "water income" and "water stockpile".
Could be interesting; I know Offworld Trading Company does, though that's more of an economic RTS than a 4x or grand strategy game. I'd feel bad for whoever tried to rebuild the balance around it if they inserted it into Stellaris, though. We'd have people wanting to tie production to planet types (so tundra/ocean would produce more, and arid or desert worlds would produce less) which would in turn skew decisions on homeworld preference... so maybe it's an idea that belongs in a new game built from scratch to accommodate the idea.