Lowly SLF here, but wanted to offer a thought:
If the hydraulic failure left them with the option of a gravity drop, is it conceivable that they might have elected to the belly landing for fear that a gravity drop might have left them with an asymmetrical deployment? Per the video posted of a failed gravity drop test on a B767 - or perhaps other factors we don't know yet - could the crew have decided that a gravity drop created greater risk than a belly landing?
Kudos to the competent crew!