As a piece of information if it can help setting the level of priority, I'm affected by this problem on a regular basis as a survey administrator (not a super-administrator). It is quite common for respondents to forget their password, and write me an e-mail to ask me to retrieve it for them (which I can't). The warning that the password can't be recovered is clearly not enough, people are just too used to be able to recover their lost passwords.

As an additional piece of info, I also advocate the use of LimeSurvey to my coworkers who conduct surveys, but the absence of this feature is one of the barriers to its adoption.