> Does anyone else find it surprising that rockets are a century old[1] and yet still seem to fail spectacularly with amazing regularity, often due to some small flaw?

Not really. Rocketry is hard.

You deal with extremes in temperature (both high and low), extremes in speed and acceleration, and you're doing it all atop massive amounts of extremely explosive fuel. And, if you feel really crazy, you do it all while attempting to protect one or more fragile bags of meat and water as you travel into an environment that wants to kill them all.

Even when you think you've accounted for everything, something like a piece of foam insulation falling from an external tank is all it takes to produce a catastrophic failure later on during re-entry.

See: https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste...