I fully agree, my first gut reaction every time I read an update about the JWST is fear that something will go wrong. I hope they take all the time needed to get it right.
I do also wonder if interactions with air / moisture / dust will degrade the components faster than they would wear out in space, the longer it's here on Earth? I'm guessing this is all accounted for too, just crazy to think of all the variables at play in the success of a project like this.
this telescope doesn't deserve any functionality setbacks in exchange for more schedule setbacks.
a telescope made late because of fixes is a fully working telescope. a prematurely launched telescope is broken for its entire service life.