Yeah I've never understood the complaints about the timer in Mooncrash. I don't pretend to be particularly good at videogames, but it's such a softball timer that the only time I actually saw the maxed out corruption level was when I actively dicked around for 20 minutes because I wanted to see the timer fail-state.
Exploration and time limits are antithetical: exploration works best when you can freely waste your time "exploring" the world which is very hard to do when the game is telling you to hurry up and you don't know the real level of urgency.
Most people don't want to test the level of urgency because it kills their immersion hence a catch-22: either they check the hidden timer and it ruins their immersion or they don't check, they rush the game and in the end they feel unsatisfied because they could not explore properly.
Also it's funny that you say you don't understand the complains considering that the hidden timer bothered you so much that you had to "check" its urgency level for yourself