Yes, this is the case -- and probably one of the more elegant parts of Pd -- but I still think this has less to do with Pd as an expressive language and more to do with how it's implemented.

Even so, I think that a message box is not a message, any more than a message to objectmaker is an object; either way the $ values mean something different in each context -- in the messages to objectmaker they ultimately function more like environment variables or script arguments, where in message boxes they're a little more like substitution placeholders in something like a macro or a sed command. I think the current $0 meaning is consistent with this interpretation.

I think my argument might be somewhat different if dynamic patching were fully supported with an official API - a huge step would be the ability to destroy individual objects with messages (can you?)...

Matt