exactly. if you did want to add something non-nut for texture and added flavor, you could add dried cranberries or dried blueberries,coconut,sunflower or pumpkin seeds. And if you wanted to try one of those ideas but also wanted some plain, it is very easy to halve the brownie batter, add things to one half, and spread the 2 halves side by side in the pan.The seam between them will likely stay visible but you could also stick in an upright toothpick to mark the dividing line.
I haven't made this recipe, but for decades I omitted all nuts from baked goods because the folks I was baking for didn't want nuts in anything. I never had to make any adjustments. The pan will be a bit less full, but not so's you'd really notice. Since these are brownies, though, you might like to sub the equivalent in chopped chocolate as a "surprise."
Alice Medrich Blonde Brownies Recipe?