Emmanuel, I don't really agree with your argumentation about the reliance on the presence of the bean object. What's the problem with that? Obviously, the best use case is cross-field-validation: validateValue would anyway not give proper results, as a possible cross-field constraint isn't validated at all? So, it would maybe be a better idea to perform validation on the entire bean scoping only a single property?
Wouldn't it be possible to include the patch into HV apart from the discussion, whether this is a good practice or not?