Ability to OLCI may be a big deal if you want to see if a better seat has opened up (through move/cancel/upgrade) and so on.
Really though I agree with katiebell in that the integration is clearly broken in parts. The whole point of a codeshare is that it's supposed to be transparent. She books a BA flight, it shouldn't matter if it's operated by BA, QF, CX or Air Koryo. The fact that when she tried to check in for her ba marketed flight online coughped out because of the QF end forcing her to do extra to do what she wanted is very poor IMHO.
(to me this is a different argument to the Q-Eat issue which I see as a product/service issue)
I've been on any number of codeshare flights and had few issues between the operating and marketing carriers (as example, UA on LH or AY on QF/CX, QF on AA etc). I'm sure issues between GDS's can account for some of those, but then again maybe not. (eg: just booked a QF code on AA metal and had no issue assigning any seat in the F cabin) and I anticipate no issues to check in for my "QF" flights.
To me rather than policy or product decisions, this systems integration issue is purely an IT one and reflects poorly on both parties (in this case BA, who have sold the ticket, and QF who seem to be the problematic party).
my 2 cents.