For real big games, you’ll need them for sure. Not sure if I will ever produce such a big game myself, but yes I agree. This should be possible.
What I do now in order to save levels is to place many smaller maps on only one maximum sized level. That way I created e. g. about 20 small indoor maps on one level for my first game, which massively saves levels. However, we need to be careful with this. If a map is placed to close to another map the player will notice this. And if a map is placed to close to the level’s borders the scrolling will be strange. Also to shift such small maps around to reorganize the level is very cumbersome now, since we have no proper tool for this yet. Nevertheless, more levels would allow us to make our games here as big as this is already possible with the RPG Makers. If RPG Playground would allow even the same limit as RPG Maker 2003 (=9999 levels) this also could be one more reason why people should choose RPG Playground instead the newer Makers.