All of the games I mentioned above have a structure where there are two main parts of the game: A scenario you are trying to beat, and a management phase. The management phase is a bit like the part in a role-playing game where you get back to the city, sell loot, buy gear, train new skills, find new quests, and the like. But between one such management phase and the next scenario, these "landings" or "road events" have been placed. In ISS Vanguard the landing phase consists of a series of dice rolls on a table, modified by the stats of your lander. In Gloom-/Frosthaven the road events come in the form of random cards with a decision to make. The reason few people enjoy these mini-phases of reaching the scenario is that their results are overwhelmingly negative. In ISS Vanguard you might lose supplies, or start the scenario with some dice already spent, or even with some wounds. In Gloom-/Frosthaven you often take damage in a road event, or get a negative status condition like poisoned or cursed. I haven't seen any positive outcomes in ISS Vanguard, and I know that at least in Gloomhaven the positive outcomes are rare. Basically a "no effect" is the best you can hope for.

The game design explanation for this game element is to provide a random modifier to the scenario. So if you happen to play the same scenario again, it will be slightly different, because of a different random event while reaching the scenario. What sucks about that is when the reason you play the scenario again is that the negative modifier you got randomly hit with while going there made you lose the scenario. The random event makes the scenario more challenging, but that doesn't do anything positive for you, like also increasing the reward if you manage to win despite the handicap.

There are a lot of ways how you could reach the same game design goal with a system that feels more fun to the player. The easiest one is to make the modifiers you get from the random events all positive, with "no effect" being the worst possible outcome. You can easily balance that by making the scenarios all a bit harder. But psychologically the absence of a positive modifier is less frustrating than the presence of a negative one. A game (albeit a video game) that does modifiers very well is Against the Storm, where modifiers not only have a much wider range of changes to gameplay and thus make the scenarios really more interesting, they are also accompanied by extra rewards and achievements. And they are voluntary, you can see the modifiers on the map and decide whether you want to play your next scenario next to them or not. Player agency is much more fun than random modifiers.