How old are you? We might actually be eating a different banana cultivar now than you did when you were a child. The situation with the Cavendish now (that it's genetically uniform and so is being easily wiped out by a well-adapted pathogen) has happened before; up through the '50s the main banana available in US supermarkets was the Gros Michel, but they were mostly killed by fungus, which prompted the switch to the current Cavendish.

Gros Michel bananas were apparently sweeter and had a different flavor, and I've heard anecdotally that part of why artificial banana flavoring doesn't taste much like how we find bananas to taste is that it was meant to imitate the flavor of the older, rather than the modern, banana. I'm not old enough to have had a Gros Michel, though, so I can't confirm that from personal experience.

I have the same thoughts about tomatoes. Tomatoes today have no flavor compared to what I remembered. It could be the flavor notes of childhood-backyard-summertime nostalgia, New Jersey terrior, and simply explained by the genetic modification such that tomatoes could be mechanically harvested weeks before they're ripe in the field. I'm a tomato luddite.