Vertex colors for vertex only objects

My question is about vertex colors for vertex only objects like this
(the scene
There is plane with different vertex colors (r,g,b,black),
and 4 vertex (another object) - this is duplicate and delete faces and edges.
In “Vertex color” panel i have a same color slot “Col”
But vertex colors is lost!
To check it i create polygon from this 4 vertex and i have clean white

Is it possible to hold vertex color info in vertex only objects?

And last thing. In meshlab we have a handy “Points” mode. When i can see only vertex of object and !!! i can tune a size of vertex!!! and, of course i see a colof of vertex.
It will be a great to have this mode in blender.