Mad Salt Lake Idea

I think this idea must be mad, because no-one seems to have done it yet; however I don't understand what the problem would be, so I explain it here to be deconstructed.

There exist in the world a large number of salt flats that are to my knowledge to all intents and purposes barren wastelands with no useful purpose to the ecology or humans. I propose to change that.
There is no shortage on this planet of seawater so we pump the seawater back to these salt flats and create new salt lakes. This would give nice shallow water, unfortunately it'd almost certainly be too salty for anything but the most hardy algae to live in. So what would creating a new dead sea give us.

• Increase precipitation
• Cooling effects of bodies of water on surrounding area
  
• You could use it as cooling water runoff area for power plants.
• Salt production

Not major benefits it might seem except that people are suggesting building boats spraying sea water to create more clouds to combat global warming. Also there's always talk about the lack of fresh water, so here's a way to increase it.

The only problems I can see with this would be the energy cost of pumping the water (which might effectively be free if the power plant cooling is available) and the potential corruption of the water table. If that was a problem though then presumably every time it rained on one of these locations you'd get irreversible salt water corruption of the water table.