If you are recording a script the binary data can be really important. Without it, the script may not look the same when it's reloaded and played. For example, if I record a script on watercolor paper with a 50% sized watercolor brush with specific parameters, the script needs to record the binary data of the paper as well as the data block that defines the brush I used. If I don't record those, on playback the paper would be whatever the user happened to have loaded by default, and the brush would paint with whatever settings were applied to it by that user, not the ones I had when I recorded my script.
There are some potential improvements that could be made to data allocation to prevent unnecessary binary storage, but when recording a script you will always have some data stored there.
If you are writing a script from scratch that won't be a problem unless you manually paste a binary data block in there.
When recording there are two specific things that might help reduce the binary block size:
1. Select a small paper texture: If your painting doesn't rely on a specific canvas type, select a simple paper texture.
2. Select a small sticker sheet: If you're not relying on specific sticker sheets, go to the Sticker Spray and select one of the Art Brush type presets or Stamp type brush heads. The smaller the sticker sheet, the less data that tool will store when the application state is stored.