The reason triangles are used, and not squares, or polygons, or some other more complex shape is simplicity: three points in space unambiguously define a plane.
You can really see what happens with sea level rise and storm because apart from these planted mangroves and some donated telephone poles keeping the sea back, it's pretty much ruined.
Nevertheless, it's good to peek our heads outside of flatland now and then to, you know, see what it means to apply these ideas in more than just those two dimensions.
If industrial pollutants are capable of heating global temperatures to the point that glaciers begin to melt, it is urgent for us to know precisely how high sea levels will rise as a result.
But part of our goal here is to find a more efficient algorithm that only requires computing the function on as few points as possible; only having limited view of the colors of the plane, so to speak.