But not also... Because right now the way changes are integrated is using the same update mechanism if I'm not mistaken.
The very challenge of the update is that you are updating your image, which has your objects, and your changes!��
So, what if you made some changes in the core classes? update may fail on merge or even remove your changes. If you keep your method you may lose a bugfix
If there was a rename of that method you changed? what should the update do?
If you configured some shortcuts? the update may reset them
The changesets? they may be reset
And the list goes on...