I know the Gnomes do tech, but the Dwarves actually seem to have become very competent too, less of a joke and more reliable. In Twilight Highlands it's Dwarven Siege Tanks and their crews you encounter and help out, Gnomes are nowhere. The Submarine we use in Vashj'ir seems to be a mix of Dwarven and Gnomish tech for sure, but there's nothing whatsoever to suggest the Skyfire is anything but a product of Humans.
This sidelining and overtaking is clearly very deliberate, since if Gnomes were genuinely able to produce this tech themselves - they'd have taken Gnomeregan back years ago. That's what I mean by their own story being painted into a corner by their situation. They don't do anything and they can't be seen to be doing anything, because if they do too much it begs the question as to why they've not re-established themselves a new home, or retaken their old home.