Starting with MW 1.19.x possibly MW 1.18.x it is required to confirm the change of an e-mail-address with a password. This is ok since it assumes that a person logged in into an user account knows the password.
Reality has it that heaps of people create an account, put in the wrong e-mail-address (typo, etc.) and forget about their password after logout. Up till now I was able to sudo these people and help them. Now this is not longer possible.
Thus it would be good to have a way to disable this requirement, something like "$wgUserEmailChangeConfirmation" which defaults to "true"