You don't need to grow hydro, specifically. Soil works just fine :) Aquaponics is also pretty cool, and can reduce the need for fertilizers, while producing more food. It doesn't hurt to grow more food. It allows us to be less dependent on shipments, and lowers our carbon footprint.
The idea of the yard needs to go. Especially, here. We have an entire industry of people paid to grow a plant that you don't eat, and try to get people not to even walk on. It's an outdated, useless social custom. We can grow a lot of stuff, and still supplement it with crops from the lower 48, when necessary. We have a lot of wasted space, we can use for community gardens, and local growing.
This dude has some amazing ideas for making money in unconvential spaces with urban gardens.