iirc the modern banana is actually a less flavorful variety than centuries past, but not for selective breeding reasons. The more popular variety, the Gros Michel, was susceptible to a certain fungus that wiped it out by the 60s. Those apparently tasted closer to the artificial banana flavoring that is still used today and in fact are what that flavoring was based on (albeit probably quite a bit more sugary and concentrated since it's still a candy flavoring).

And then you have other produce like apples and tomatoes being bred for size and yield, since that will both net more profit and feed more people. This often necessarily means that the produce will lose flavor in the process, as well as nutritional value by weight since the size/yield increase is mostly just the crop taking up more water. (I think the genetic modification you mentioned is in some part meant to correct that inverse relationship between yield and nutritional density, but I'd have to read up more on the subject.)

So I think you can just as much argue that it's not our tastebuds being ruined so much as produce itself being considerably less appealing to them.