That's not a coincidence. It makes perfect sense that a large heavy aircraft like the 380 will be harder for wind and air pockets to push it around, just like big ships are far more stable than smaller ones. There's a world of difference between coming into (say) Singapore with its turbulent tropical air on a little a320 and a giant like a 380.
I've been on narrowbody flights where we bounced around like we were inside a washing machine; in a 380 i've barely ever had to even pick up my drink!
No. Longer immigration queues could be solved by the government adding more staff, but they cannot be solved by the airline adding more staff, and the airline is the one buying or otherwise choosing to use the plane.
Even at SFO I've gotten to fill the immigration questionnaire a few times with a self-service machine, greatly reducing the time spent on the process.
I also live in Australia and have flown both the Dreamliner and A380 and if possible will always choose the A380.
Far roomier plane, much quieter and even though it may be just a coincidence every time it seems to suffer far less turbulence.