The reasons you should care about this are laid out better in this video, which explains a lot more of the details:
At 3:26 they nicely explain about the reduced voltage required (which means it's more efficient) of 1.6 Volts instead of 2.3 volts of the 1.2 volts you could potentially recover in a fuel cell.
At 3:55 they explain that there are no precious metals involved, which means it could be scaled quickly once they tweak it.
At 5:15 they explain why they started experimenting with cobalt compounds to avoid precious metals
At 5:45 they explain the nifty catalyst they set out to make and investigate
At 6:05 - it didn't work... serendipity occurs instead
At 6:55 - they don't know how it works... but they are willing to learn
So... here we have a new way of efficiently converting excess electrical power to hydrogen and oxygen. This is a critical part of the cycle required to store energy for later use.
I consider this the modern physics equivalent of inventing the first granary. It's a new place to securely store a harvest from the sun.