Hello Commanders,
thanks for the feedback, we might be able to include this info in the future, however world size and slots correlate; and since we usually start worlds with persistent starting slot numbers (15.000 for Tiberian and 10.000 Wrath, 5.000 for Veteran and Firestorm iirc) the world size would be relatively consistent for every world type, putting the Fortress always at its centre.
Basically, the amount of starting slots determines the min. size of a world, while the size of a world determines the max amount of starting slots. So while we could make a 500x500 World with only 5.000 starting slots, a 200x200 size world with 15.000 slots would not work.
For that reason we provide the amount of starting slots with the world description, as we think it is the more interesting metric for players starting on a world.
Of course the increase of level is more steep on a small world with higher levels. This, combined with the moral malus might be a bit too punishing for most players so we will try to avoid this combination on future worlds.