From the people I've spoken to non-stop is a HUGE benefit.
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Yes, HUGE.
I've gone back to an old flight combination (not to USA) I used to do which involves transfering at AMS and I'm actually going a day early due to a deep distrust of KLM flight timings and the ability of AMS to transfer a bag from one plane to another.
Especially as they 2 legs can't be ticketed together these days
I would pay a reasonable premium for a direct flight.