Should a new army be started again?
Don't. The goal of the Challenge is to empty the wall cupboards, not to encourage us to launch us in a new project which will remain at the stage of " to finish, one day…".
Yes, and you are impressive. However, it's one crowned motivation and the proof that one can assemble an army of consequent size without losing his motivation for painting.
Because it's possible to play 40k and apocalypse. Playing 3000pts armies gives you the pleasure to play big points units.
Why impose the standard diagram?
The Challenge's goal is to be able to play 40k and Apocalypse. This is why Super Heavys aren't included in the 3000pts. Free with those which are inspired by the Challenge to assemble an army including a Apocalypse formation . That will make more large animals at the end of the year.