I created this because I was frusterated by having to change the integer values when the environments changed for my projects. A simple update of PHP 5.6 (I think it was PHP 5.6.16 to 5.6.17) changed the integer values, which are usually what is suggested to be used in parameters.yml or config.yml.
By using the constants, you don't have to worry about stupid stuff like that. (Since that's what they were designed for.)