This. Even a little terrain is a lot more dynamically interesting than the ocean. There are also strong heat / surface moisture gradients on land (think edges

This. Even a little terrain is a lot more dynamically interesting than the ocean. There are also strong heat / surface moisture gradients on land (think edges of forests, cities, coasts), which play a big role in convection. By comparison, the ocean is an infinite plane so the dynamics are much more dependent on large scale forcings like the Earth's rotation and there is less local variability.