Brink is a valuable reference in terms of both character design and in-game character customisation settings.
From seeing a presentation by one of the concept artists who worked on Brink, I learnt about the teams design process. The use of different character classes was conceived to allow for a diversity of different fighting and movement styles. The main separation between these is the light medium and heavy body types that the player can choose to have, each of these will impose a set of animations/move sets for the character. Alongside limiting them to certain attributes like speed etc.
This is one of the first things that I looked at for this brief, how do industry games incorporate different character classes and move sets for them. For the Brink dev team this was one of there struggles, as they had to cut down on some ambitious designs to allow for the actual realisation of the designs in 3D models. This is why they have the 3 start up sets of body shape, as later down the line it saves on the amount of animations, models and rigs that they need to produce, which also means less strain on the in-game render speeds. So in terms of the character classes Brink was designed to allow for a good game performance over amount of choice for the player. It does however offer up a wide variety of options in specifics for the visual aspects of the characters.
I think that the restraints that the Brink dev team had are something to consider but when you compare this to other games that are more in the RPG genre then they offer a lot more choices to the player than Brink does.