Hetmyer, the 25-year-old batter, was West Indies' leading run-scorer in their disappointing 2021 T20 World Cup campaign, making a valiant 81 not-out off 54 balls against Sri Lanka, but has been left out of their ODI and T20I squads to play Ireland and England after failing a fitness test.
Hetmyer has now been omitted from several West Indies squads on fitness grounds, having also missed the recent tour of Pakistan due to personal reasons, and Simmons said that it was "heart-wrenching" to see him fail to reach the minimum standard again.
"It's the same old, same old," Simmons said in a press conference on New Year's Eve. "He did his fitness assessment in Guyana last week and came way below the required mark.
"It's something that's heart-wrenching because you know that you're part of this team and you have to continue to be a certain fitness to be part of this team, and you keep letting down your team-mates.
"It's disappointing and again, we have to go back to this and I think it's something which we shouldn't have to be going back to all the time. He keeps letting down himself and his team-mates."
Simmons also addressed Chris Gayle's omission from the squad, after Cricket West Indies chief executive Johnny Grave had mooted the possibility of a farewell appearance in the one-off T20I against Ireland in Jamaica.
Local Covid-19 restrictions have forced that fixture to be staged behind closed doors and reports in Jamaica have suggested that a testimonial match for Gayle could be held later this year in front of supporters at Sabina Park, as his international career draws to a close.
"It's something that I would like to see start in our cricket," Simmons said. "But when we sit down to select a squad, we sit down to select the best squad for the upcoming series.
"If it's a case where a send-off is to happen for Chris, then for us to select him, if he's not part of our make-up, it has to come from above us. I can't really say if that's going to happen later on in the year."