Because the "flaws" you keep pointing out seemed perfectly logical the first 20 times they happened but suddenly we're supposed to believe it's a huge problem now. More importantly, your reasons for pointing out that flaw keep changing, as if you haven't really decided what the reason for pointing it out really is and you keep thrashing around trying to find one that works.
It's like if you have already decided to hate something, you will invariably come up with a reason to do so even if that reason doesn't make sense.
Discovery has its plotholes like anything else, and there are things we wish they did better or made more clear. Shenzhou not being scuttled due to the crew's not actually having a reason to do so in the first place simply isn't one of them.
It's like having a student asking you for feedback on his essay and whether or not he developed his ideas properly and the first thing you point out is that the second sentence of his first paragraph ends in a preposition.