Visual block insert strips indentation

I assumed this was a known and low-priority issue, but today it annoyed me enough to look into it, and if I understand correctly (fakevimhandler.cpp:2634 or so) the indentation is stripped on purpose. This and the fact that I couldn't find any open issue for this made me realize I'm probably doing indentation wrong.

What's the best way to fix this? What breaks if I just remove that indentation stripping? Or does it make sense to special case "someone inserted just white space in visual block insert mode"?