My apologies for not wading through every answer to see if I'm duplicating anyone.
In my experience, an image with low contrast requires a contrast boost after the scan. And whenever contrast is boosted, flaws and artifacts start to emerge. The most obvious will be increased grain, dust, and scratches. So an image may have great detail, such as a collapsible Summicron that I used to have, but I'd rather have a higher-contrast lens and high contrast film for scanning. That's why I miss Plus-X, which needed very little boost after scanning.