WBAP adds more variants for wooden buttons and pressure plates (namely Spruce, Birch, Jungle, Acacia, and Dark Oak) to enhance your vanilla or, more likely, modded experience in 1.12.2. It also increases the yield of button and pressure plate recipes to the more reasonable two per wood plank block (two buttons per recipe and 4 pressure plates per recipe).
If you want more than just the wood plank buttons and pressure plates check out the wonderful More Beautiful Buttons and More Beautiful Plates mods by Kreezxil.