Hi there,
The pedal is configured like that in order to give you better brake feeling and avoid bottoming out the pedal and locking up your brakes. Obviously with cars that have ABS that's not so much of an issue but in cars that don't have ABS you really shouldn't be pushing the brake to 100%; in fact where you should be pushing it to is roughly where the progressive spring starts to get stiffer.
Instead what's highly recommended is that you anchor your chair. A set of castor cups are one suggestion, or even
sitting the back wheels of your chair into a pair of trainers. Once you have your chair locked in position then you'll be able to feel the benefit of that progressive spring.