The direct will probably save you a couple of hours over a stopper
That will be attractive to some passengers and I'd guess overall you'll burn less fuel than adding an extra landing & t/o so it's good for the airline
As ever it all depends on pricing - there are probably enough passengers flying London-Perth and v/v each day to fill a 787
But you won't get any connecting traffic from S & E Australia as it's 4-6 hours flight time to Perth plus a connection - much faster via DXB or SIN