Hello,
the list of watchers was driving me crazy for a long time.
I created a patch against upstream version of Redmine:
http://www.redmine.org/issues/15833
and also patched our instance:
http://www.redmine.org/attachments/10960/0001-Adding-watcher-icon-for-new-issue-form.patch
(also stored in /srv/redmine/0001-Adding-watcher-icon-for-new-issue-form.patch
in case we want to revert it)
On the New Issue form:
http://projects.theforeman.org/projects/foreman/issues/new
the huge list of watchers is hidden by default and only shows when you
clink on the edit icon.
Since Katello guys are going to use Redmine, we do not want to scare
them on the very first form of the thing 
Redmine is nice, no need to
worry.
···
-- Later,Lukas “lzap” Zapletal
irc: lzap #theforeman