Hi Mike,
but default columns in Row grid are equal, it's how it works, as I remember since SPPPB 3.x , I even made a video on youtube about that.
But if we talk about Addon itself (they are not columns!), they are like the elastic rubber box. If you don't want to use their settings to set static height or custom CSS to reduce img size, just use images in the same size (height) in addons. Decide what will be easier (for today & "tomorrow"), and do it.
Alternative option for hard-core users only, set border & shadow effect for each column, not addon itself.