Edge groups could be a game changer in overall modeling workflow and can be a huge step forward in productivity - both modeling for games or movies (high poly, mid poly) but also concept art when changing things really fast in fly (non-destructive) is helpful and sometimes important.
The reason is that non-destructive nowadays is crucial. Having possibility to assign bevel width for specific line would be amazing, because thanks to that I can control object bevels more freelly. Bevel weight is cool but not everytime. Controling different type of bevels through angle is bad and you need to be careful to keep good angles values on mesh.
Below is simple example how this could look like
I know that there are some addons that allows to make your work easier and faster, but still first, it’s often based on features that Blender already have, and second thing I don’t really like complex addons because they are often writen in own artistic thinking way. We should make Blender more consistent.