I see your point. Hopefully they made it structurally sound to help support its own weight.
I think though, that with the emphasis on low noise, their pumps are low pressure and so they want it right on the water block. In theory it shouldn't matter but logically having the pump nearly directly forcing water through the block should give it the most pressure it could get. These AIO water cooling setups are limited by their blocks and especially pumps. You can see this by increasing fan speed and seeing no temp decrease at all. Then increase the pump speed and notice the temps plummet.