Softer bushings are easier for your hanger to compress, and therefore it is easier to turn on softer bushings. Harder bushings result in stiffer turns. Importantly, how tight or loose you keep your bushings also effects your skateboard's turn responsiveness.

Should bushings be tight?

They should be snug, but not ridiculously tight. My H&R bar came with teflon bushings and they took some muscle to open up and get on, but once they were on they would spin with some effort, but not spin freely if that clarifies anything.

Are harder bushings better?

Bushings come in pairs. The top bushing on your skateboard truck makes your board turn, the bottom bushing can be adjusted by tightening or loosening the nut to make adjust responsiveness. Loose means better turning but less stability (especially at high speeds) and tight mean more stability but less responsiveness.