Removing HMs was a mistake. HMs like surf defog, cut, and rock climb gave a much richer and more rewarding experience when exploring the regions. They made backtracking to previous routes more worth while by hiding secrets behind organic feeling roadblocks, and as a result rewarded the more curious players. It made every excursion into the games' wilderness a richer challenge, making the player engage in difficult team building choices and balancing high damage moves with utility moves. They also gave the player a reason to keep shitmons they loved in their party to fufill a utility role.
Removing HMs takes away these extra layers of adventure to the game and makes them one step closer to a battle simulator with hallways between the towns.