Well as often it's a matter of viewpoint I guess...
As for being cumbersome, um, no? I am doing right now the exact same thing I'd need to do to enter connection information i.e. typing text in a fairly large content area.
Not really. The actual workflow would be, from a user standpoint:
1 - ask you to make the ticket private (considering about 30% of my users spontaneously offer credentials, by experience).
2 - Wait for an email saying your replied
3 - Make a new post with the credentials
4 - You copy/paste them and remove them from the thread into the Manager's note, then answer
5 - Maybe make the ticket public again (everyone knows they are using sh404SEF or wbAMP, that's what they are asking support for. Only a handful of tickets actually disclose real information - besides credentials)
Compare that workflow to: nothing
With a a private custom fields, user can post sensitive information at any time, without you doing any copy/pasting, changing ticket status, and most importantly having to wait a back-and-forth post to go ahead.
why giving edit access to users is bad.
Didn't say anything like that. Indeed, we also consider tickets as a historical record of exchanges, that should not be modified. But a single private and editable field does has nothing to do with that.
Finally, about the users getting the extra fields wrong. That would be a strong indication that you have too many or too complicated fields. When we started having that problem we pruned the custom fields to the essentials. Now we don't get wrong field contents by accident, only by ignorance. Either that or we have too many time travelers who are using Joomla! 6.4 ;)
Actually so far I dont have any such field. I dropped the J!; PHP and such questions a long time ago, and ask them only if relevant.
No worries, that was only a suggestion. I quickly put that together using a plugin. You can close the ticket now.
Rgds