I'll throw out a guess that it's because "My 1000’s of users are mostly over 75 yrs old so keeping things simple is important."
Regarding "I forgot my password", you don't even have to convince them
to click on that link. You can click on it for them. Someone who is invoking the "I forgot my password" (ucp.php?mode=sendpassword) link is not logged on, and could invoke that process for anyone whom they know the email address.
So if you received a password reset request from GrettaSilverFox1943@aol.com
, you could go to a logged-out session and invoke ucp.php?mode=sendpassword for that email address. You could even customize that email template a little bit, so that the standard email phpBB sends feels more like a "personal response", even though you're initiating the same reset ability everybody already had access to.
Yes, even if you did like the idea of using the existing reset process rather than "resetting back to a fixed and known password", an extension that lets you initiate this right from the ACP would still be helpful. A kind of "Force password change" option, just like the existing "Force reactivation". So that you don't even have to know or cut-n-paste the email address, nor go to a logged-out session to invoke the process.