Probably because the nature of the app store works against you.
You can't be sure when Apple is going to approve an app. And setting a release date far in advance does you no good because of the way the listing system works.
So you worry about getting the main version out first, and the lite second.
If the Lite gets out first, by the time the main gets out people have moved on.
If the approval/listing service was better designed you could just submit with a fixed date for both and not have to worry about being approved a week before and having that bury you in the what's new list.
Hopefully this name will update soon as I requested a name change. I'm no longer affiliated with Atommo games.