Tried babylonjs week ago when they released new version. It was my first experience with 3D in the browser. But must say was very positive. I was able to do everything I wanted. The only bad was the lights shines through solid objects, so modeled room lamp is visible from the outside of the building :).
I didn't tried threejs though. So sorry for being bit of topic.
This behavior is expected. Without raytracing, lights are calculated locally for the object, without taking other objects into account. Unless you enable shadows, which add some computational cost but can prevent lights shining through walls/objects.
I didn't tried threejs though. So sorry for being bit of topic.