Static Mesh reimport not updating Vertex Colors

No, it shouldn’t be default, because the majority of people change the vertex color in the editor. Most famous example is using the vertex color like a paint on walls and grounds to lerp 2 textures together for variety. I think cloth simulation is also saved in vertex color. If you re-import your mesh from your 3d app, all your work would be lost, that’s why the default doesn’t override.