I brought up a similar argument in " Reusable Items to Substitute HMs for Easy Access to Dungeons for Grinding? ." I think since even the main series has discarded HMs due to annoyances, it’s silly to have them be such a key feature in a Pokemon Mystery Dungeons game. Although I understand the intent, I think as the main series has demonstrated there are alternative ways to content lock in a pokemon game. So personally I support anything that makes HM blocks more practical, one way similar to what you are saying, make the game more open worldy, additional suggestions would be to
A. Make barriers blocked by a linear dungeon completion progression instead of HMs
B. Have HM blocks in front of dungeons but have a chimecho outside the block for easy HM retrieval, and remove them in the overworld