I've experimented with building a submersible robot and - by far - the most challenging aspect of the build was creating an interface between the motor and the propellor that was waterproof in a reliable way. (applying grease or something hydrophobic on a shaft lasts only so long)

By abstracting away that schlep for me, - a schlep, which is usually the least interesting bit about a machine - these guys might be able to create something analogous to Arduino for marine robots. Before Arduino, you needed a complete test bed to get a micro-controller up and running. After Arduino, you usually focus on what you want to do, instead of getting the micro-controller to work. That shift makes creating something extremely accessible, allowing anyone to jump in and try things out. A line of products like these, might actually make robotics far more accessible than any number of kits before it. In other words, this could be the start of something incredible.

Edit: I just realised another way of phrasing what they're doing. Imagine how hard payments was before Stripe came along. These people are basically the Stripe for marine robotics, which is really awesome.