I don't actually think they need remove it. But giving aerial manoeuvrability to a single race, along with double jump AND a glide... That's arguably more impactful in terms of movement than what anyone else gets. If the dash was changed to a wing flap (a much shorter dash), akin to what the Human or Half-Elf dodge rolls are, they could retain the ability to be the only race in the game, that could dash while not touching the ground. But they couldn't just double jump, dash, double jump, dash and suddenly outpace every other race in the game, with no risk.
The Stealth bonus I'm still oppose