When XP globes were first added, there was no last hitting and minions would just drop globes where they died. However, this was obviously a huge nerf to Ragnaros, so they gave Lava Wave the ability to pick up globes from the ground like a hero. With last hitting now giving direct XP, this was redundant and only gave Ragnaros this weird ability to suck up sitting XP like an Abathur hat.
So yes, it’s only a minor change.