Anyone can cherry pick a few design choices they don't understand and say it was incompetance.

How many contractors arrive on site and incredulously say "what was the last guy thinking?" and actually mean it?

Just because we don't understand the reasoning yet isn't strong evidence of incompentant designs, it's more evidence of our own incompentance.

We used to think that the appendix was vestigial and useless, we used to think that 'Junk dna' was a thing. With more time and research we now know how wrong we were. I'll take the downvotes and predict that we'll keep finding out how wrong we are long into the future on this subject.