I'll ignore the gratuitous attack for now (just look at how many people I've helped over the last years on this forum and elsewhere to see how ridiculous your assertion is).
You could have started by explaining what your real question was and why the answer already provided on StackOverflow was not satisfactory to you. I can't guess what's going on in your mind.
So I still don't know if that will answer whatever questions you really have, but I think that someone ought to submit a pull request with these changes so that we can open up this scenario more easily in a future release. But in general no, it's not a good
idea to change core code if you can help it. If you can't help it, it should be submitted as a patch.
As far as I know, the MVC client side validation as it exists today did not exist when that code was written, but I would be wrong on that, and it may have been removed because of lack of time to test it in the context of Orchard.