The present core "child themes" (City, Ninjago, Creator) are a far cry from the golden era during the 1990s (Castle, Pirates, Space). Back then, most bigger set

The present core "child themes" (City, Ninjago, Creator) are a far cry from the golden era during the 1990s (Castle, Pirates, Space). Back then, most bigger sets had baseplates (flat or 3D), the latter primarily used with castles and fortresses. You could easily combine sets from the same theme from different years and build something completely new which feels like a new set from the same theme. The variety of parts and colours wasn't so huge. With a modern theme like Ninjago, most of the sets are some imaginary vehicles with very specific parts and colours. You could probably build a new vehicle from the same set, but combining different sets is much less enjoyable. The few sets with buildings have no baseplates and the structures feel very airy and unharmonic.