as one of the [cue to carrol cox] posters, i take great umbrage! ;-) kidding aside, this is a good idea, except for recipient list growth when reply-all is used to send to the list. not only does this [in some cases] duplicate messages to the person being responded to, but it is also a bloody pain to see 10s of recipients in the list headers, which ultimately leads to wasted SMTP connections/conversations for future responders.
non-tech version:
if the above suggested change is made, then the lbo-talk mailing list server will instruct your mailreader to send responses, when you click on "reply", to the original individual sender of the message, not to the mailing list.
what about when you do want to reply to the list? then you would need to use the "reply all" or "group reply" button on your mailreader (i am being GUI centric since the non-GUI folks probably know all this too well).
this means you have to remember to 'reply all' when you want your response to go to the list.
when you hit reply-all, your mail program marks your message to be sent not just to the sender (the individual) but all other recipients, i.e., the list. this means your response message will now have two recipients: the original sender, and the list.
the original sender potentially gets two copies of the message, as a result.
if person Y responds to your response (using his 'reply all'), his response will now be addressed to you, the original sender, and the list.
this obviously gets ugly.
back to tech talk:
now, IIRC, mailman has a configuration where it weeds out listmembers from message headers. this mitigates the above recipient address creep, but still leaves other problems open.
--ravi