It seems that the selection process optimizes for either liars or dumb people who are easiest to emotionally manipulate. If you appear very reflective and capable of complex thought, you're a risk.

You could've said, you're open to whatever sentence, you make no prior commitment and will decide for whatever sentence is appropriate based on the court proceedings and the law as given by the judge. But they would have called bullshit on that too, they are good at seeing who is a difficult person to work with from their POV.

It's a very broken system and I'm glad to live in a civil law country. The power imbalance is huge. The lawyers are incredibly well prepared regarding tricks around jury psychology but the jury are selected for being the most naive people possible. If you seem too much of a smartass to them who knows their tricks, you're out.