If you add triple-redundancy to all the mechanical elements you build a rocket that probably can't fly - which is certainly very safe, but maybe not so very useful.

I'd guess the problem has more to do with insufficient testing than insufficient design. It's likely the initial batch was easily up to spec, then there was little or no testing of further batches.

Easy mistake, IMO. If you think about the number of critical components, re-testing everything before every flight would be a huge and very expensive job.

I wonder if SpaceX are going to do less business with the strut supplier in future.