The only logic I can see in having groups would be to seperate out which members have which versions of Trainz. (A member, for example could be part of the Trainz 12 group, Trainz 2006 group and UTC group.)
Though, if this is the case, I'd rather have the old method of having the station stops above as it makes it SOOOOO much easier to work out which version of Trainz people have registered and as such, give them better tech support (Away evil hackers, away! I shall tie you to the tracks in front of a high speed bullet train!)