I like the holding the button method of input. It feels like you're compressing a spring, or bending your legs to store power for the jump.
Jump on button press will allow people to react to stuff instead of pre-emptively making a decision on whether or not to jump, so there's something going for that too.
Honestly, this is up to the design of Caged Element, and they've already chosen. If the community would unanimously agree that the current method sucked (e.g. EMP), they'd change it, but considering there are plenty that like the holding mechanic, I'm sure to say the holding mechanic will remain in place.
Jumping in midair... Meh. Would the game really benefit from that or would that make gameplay messier just for the sake of adding features?
As for Queadah's request for more effects, they'll come in eventually. Keep in mind we're still quite a bit away from the polishing phase.
And hell yeah, another Abandoned Attol lover