>>57038904Because GS was made in 710KB and HGSS had 57MB of space on-cart, They kinda needed to add pre-existing filler, because the new-old style shit they tried by adding new areas to Kanto in FRLG didn't take with players.
There's also the fact they migrated VGC to HGSS on release, so needed to offer training to those who may need it. When ORAS rolled around, getting an opponent to fight was as easy as going online and clicking the Vs. button, so didn't need to offer offline training to people who may not have had an ability for regular competition like back in DS days (needed a wi-fi dongle to connect the phat and lite to the internet, which cost extra and was separate).
