See this video for motivation. Before this change, the road network can be placed as a root scene member, but then when brought into another scene, you have no way of moving it around since it's not a spatial (or hiding etc). While the intended use case of roads is not to be precomposed into a scene like that, there are still lots of benefits of being able to shift around the entire road network with ease, and we'd get that with ease by turning all of these items into spatials, as the parent hierarchy then starts applying to translation etc.
See this video for motivation. Before this change, the road network can be placed as a root scene member, but then when brought into another scene, you have no way of moving it around since it's not a spatial (or hiding etc). While the intended use case of roads is not to be precomposed into a scene like that, there are still lots of benefits of being able to shift around the entire road network with ease, and we'd get that with ease by turning all of these items into spatials, as the parent hierarchy then starts applying to translation etc.