Instead HMs should not only be powerful moves that do not waste a precious slot, but also be unique and maybe have multiple uses. Perhaps if Incinerate was a HM you could use it to burn down trees and clear a path, but also clear insect spider webs as you explore dungeons. Flash could illuminate caves, but also draw in Ghost Pokemon when used at night. And what about using the weather TMs, e.g. Rain Dance, to change the weather in your immediate area which changes the Pokemon you might encounter. Psychic/Teleport could move you and your Pokemon across a ledge or something. Brick Break could clear rubble or break large stones block your way. Etc.