I think the most annoying thing in this game is that bosses are set on a specific "game date", meaning if you don't rush the game, bosses gets harder and it's annoying. I can understand about giving a sense of "realism" and days matters, but it shouldn't be about bosses imo. Bosses should "start getting stronger" when you defeat a previous one, otherwise like you said you cannot even enjoy it fully, explore, do some mistakes etc.
Maybe, when the game would be complete, I'll personally mod it so this will not happen. Meaning that bosses should start get stronger when you "find them". It will not be like the author envision his game, but this is why it would be a mod.