This is a fair point. Your change will not be overwritten if I do not upgrade the version in next release or if you upgrade your version (but then you may loose the benefit of a next update). With that said this action is not a core component, it is just used by the create workflow to validate the properties.

I should have mentioned it but a presentation validation accept only 2 states : an error string and when it does not validate and "" when it does validate so I cannot display a warning.

Maybe I should just drop testing null properties - if someone get some he will still be able to run the update type workflow to remove a useless property.