There are lot of things they should have done and that they should have not done.
They should have added new types.
- sound and cosmic type could have been added in Gen III
- light type could have been added in Gen V
- keep doing pre evo and evos in Gen VI onwards
- make trading not a...
The 2D regions are rather more developed than 3D ones. All of them.
Pokemon versions doesn't fit in 3D as well as in 2D, they just make it 3D because they feel "forced" as the videogame hardwares advanced a lot, so there was no point in still drawing the games in 2D.
Nice theory dude. But GF doesn't care much about bringing sense to the series since they introducted the megas in generation VI.
If they ever wanted types to make sense they would have added more in the past years (sound and cosmic type specially)