Don't forget all airliners are supposed to comply with various regulations, national and international, regarding the likes of obstacle clearance, climb gradients, etc. I doubt the 380 is any "worse" lower down than a 744, but being bigger it sure looks different. Dare I mention that even the earlier A340's had too comply with the same regs...
As T6NL
has pointed out the big twins are mostly very overpowered compared with a 4 holer... as long as all engines are running.