It makes sense from QF's perspective. To Europe, they're most competitive out of PER and SYD. They just aren't that competitive out of MEL. It's a different story for the US where they're more competitive out of the East Coast cities. It doesn't surprise me at all that the first A350 out of MEL
might be to DFW rather than LHR.
On a personal level, I'm very happy with this announcement. There are far superior alternatives out of MEL to Europe than QF. And I'd very much welcome the ability to fly F on more routes to the US out of MEL where there are fewer superior alternatives.