The interesting thing is that rows and columns wasn't the groundbreaking concept that energized Bricklin to implement it, the fundamental novelty is the automatic recalculation feature. The origin story of how visicalc first formed in his mind is varied, but every version the fundamental insight is that you write expressions symbolically and the computer substitutes so when you change the value of the symbols the computer automatically recalculates.

The idea of a grid came to him when he was implementing and had to define the way you reference values symbolically in your expressions, it's not a problem in traditional programming because we have variables and functions and objects and a metric ton load of other named abstractions, but he wanted a GUI. At first he experimented with arrows but the graph very quickly became too unwieldy, then he hit upon the idea of a grid to address and reference values as will as display them. Basically a two dimensional computer memory where the addresses is the (row, col) pair. Simple yet elegant.