Why do you insist on collecting email addresses even though
$wgEnableEmail=false?

Wikis may be discussing sensitive topics or located in countries with
repressive governments. Collecting email addresses makes the wiki a
target for police, phishers, and could get the user fired, outed, or
even arrested.

Just check $wgEnableEmail before all other email functions, like you
do here:
specials/SpecialUserlogin.php:878: $template->set( 'useemail', $wgEnableEmail );
templates/Userlogin.php:82: ... if( $this->data['useemail'] &&
templates/Userlogin.php:172: <?php if( $this->data['useemail'] ) { ?>
(However note Bug #10158).

happy.melon.wiki wrote:

There is no "you". MediaWiki is built by a collaboration of volunteers; you must already know this. No one is "insisting" on anything, it's just that, in the 30 hours between your posts, no one has happened to look at this bug and think it interesting enough for them to spend time fixing. Certainly no one has thought it of such dire importance as to warrant a hackish "quick fix". If you think it *is* important enough to warrant attention, you are encouraged to develop, test, and present a patch yourself, which can be reviewed and applied.

See also bug18549.

Created attachment 6138
move $wgEnableEmail test to outermost, fixing the bug

attachment wgEnableEmailOuter.diff ignored as obsolete

Created attachment 6161
Updated patch so applies to the rapidly changing code. Purposely not indented. Run a beautifier after applying.

Attached:

One can also do array_push($wgHiddenPrefs,'emailaddress'); for now before the patch is applied.

Done with r52736.