Thank you for the proposal, Benchtech, and for the discussion.
I think it makes sense for accounts created from admin panel, indeed, as pointed out before.
I don't know how many cases of admins resetting passwords exist (for older accounts), since users should be able to reset their passwords (if one forgot their email address or has another one, they can request the admin to set another email for them, instead of resetting the password).
All things considered, I incline to add this one way or the other to SMF logins enhancements - or rather its ecosystem of official mods. I don't really see the "global" option (all users must reset passwords next time) as core feature..., for the reasons pointed out above - but for the same reasons it may be useful to develop a mod/tool that will allow the admin of a forum in need for mass-reset of credentials to have it at their disposal just in case. Thank you for the idea, it never occurred before, that I can remember, anyway.