A few millimeter (therefore a minimum of 2) is quite a lot.
I don't see the thinnes as a problem, i'm more curious on how this was not detected in there endurance tests. Can't imagine at all that there are not 100 macbook pros open and closing all day long somewhere.
There definitely are, but there are many potential factors that impact how something wears: most notably temperature and humidity. I reckon all it takes is a few opening movements in cold and dry weather to weaken the rubber or plastic in such a way that it'll fail, but much later. But I'm just guessing
I don't see the thinnes as a problem, i'm more curious on how this was not detected in there endurance tests. Can't imagine at all that there are not 100 macbook pros open and closing all day long somewhere.