We're going in circles now. As discussed earlier,

Not in circles. I keep asking the same question, because you haven't yet answered it.

None of that consistutes a need.

1. the user is freed from having to remember obscure DSN formats"

   They don't have to "remember". They just cut and paste from the appropriate DBD docs.

   Your way, they not only have to look up those docs to find out what each particular DBD requires; they also have to look up your docs to find out the "standardised names"; and then work out how to map bits of those opaque tokens to them.

   And then wonder what to do about the names they don't have bits for; and bits you don't have names for.

2. and can inspect the individual pieces easily

   Why do they need to "inspect the pieces"? How will they use that ability?

   Just having that ability, 'because you can', isn't a reason for having it.

   Just being able to use that ability isn't a reason for having it.

   There has to be a purpose for using it. And you've obstinately failed to suggest even one.

3. The "standardized names" I talked about in my hypothetical DBI example exist in Rose::DB: host, username, password, database, driver, etc

   Now that is a circular argument.

   They have to give you them in bits, because you have names for them.

   And you have names for them, so that they can break them into bits.

   But (again) for what purpose or benefit?

4. And don't forget, for those who do want to use DSN strings for some reason, Rose::DB will accept them as input

   So, they don't need them. And neither do you I suggest.

   I've looked. Not exhaustively, but I have looked. And I cannot find one place where you do anything with those fields beyond set them and get them. Not one substantive flow control, validation, ... nada.

Furthermore, your continued characterization of Rose::DB objects as glorified structs

I have never characterised Rose::DB objects as such. Just the breaking apart of DSNs.