Why haven't they done away with HM's yet? Key Items that serve the same purpose of HM's would be such a good alternative. Instead of taking up a move slot in a Pokemon or requiring you to capture an HM mule, they wouldn't take up any space and could be given out by the same people that give out HM's after you collect the needed gym badge.
>cut could be replaced with a saw
>surf could be replaced with a surfboard or kayak
>fly could be replaced by a balloon
Is tradition the only reason to keep them as a mechanic?