I've been curious about Terra worlds.
Wouldn't it be a more viable strategy to concentrate on collecting capitals and forgo the new world?
Maybe so. This strategy is definitely not as feasible on higher difficulties and larger maps. I play almost always on Terra, monarch game right now, and I haven't touched the new world since I expand sufficiently enough anyway (and if I need more land, I simply take it from others. >=D).
On top of everything else, the AI is quite a bit more aggressive, so diverting your resources heavily to another continent could be a recipe for disaster.