Currently, students are required to input user ID, password, last name, first name, e-mail, city, and a message. All but the last appear on the user account list, and most appear on the gradebook. However, at most colleges/universities, students are administered by a student ID number. This is the one piece of information that needs to be available for searching, gradebook sorting, and accurate user account administration.
Non-English speaking students (I use Moodle for TESL in Japan) frequently put their surnames in the "first name" field. When they write their name in the local script, the sorting algorithm sorts the names wrong. Student IDs would solve this.
I am aware that there is a similar field buried deep in the user profile. To see it we have to open each single user profile, and we cannot see it, nor can we sort by it in the gradebook or course participant list.
Those admins/teachers who like the status quo can simply refrain from setting student ID as a required/sortable field.