I agree desalinization is a far more sustainable solution than this is, it is just they go about desalinization the wrong way. Desalinization works great on a small scale and is used currently by many resorts, Islands and tropical homes, however you run into problems when you try to desalinate water on a large scale. " death by a thousand paper cuts" to solve the problem would be more effective instead of trying to desalinate the water in bulk, they should desalinate it in route to the storage facility, and bulk store the desalinated water instead. As for the brine, instead of dumping it back in to the ocean, it should be put to use and many uses have been experimented with in recent years, such as using it in building materials, for example:
http://www.greenoptimistic.com/eco-friendly-restaurant-air-purifying-walls-made-salt-20150122/#.VTy5ZyFVhHw
http://www.hindawi.com/journals/jwm/2014/389316/
http://www.biova.de/en/salt-building-materials
We actually want people to use more water not less in planting air filtering temperature lowering soil loss reduction plants to prevent more water from running off into the ocean, in order to do so we have to be able to return the water running off into the ocean back to the freshwater source and the only way that can be accomplished is via desalination of some kind. The problem isn't that " people are using up too much water" at all, it is that the water sources are not being replenished, and if they will not be replenished naturally, we have to find a method to do so manually. The water isn't actually getting " used up" it is being displaced, and we do have the ability to replace it, we just have to put forth the effort to do so.