Yes, I agree. A smaller plane would be handier.
However, Qantas believes in using 4-engined aircraft for these long transpacific flights which take place mainly over water.
Currently it uses both the A380 and the B747-400 across the Pacific. But the B747s are being phased out.
Qantas has no B777s in its fleet. And it has no plans, at present, to acquire any of them.
It has ordered a number of B787s for delivery in the future but, at the time of writing, it has not indicated whether or not it will deploy these on the transpacific.