A reader writes:
I sold produce for a few years so I figured I was qualified to add my two cents here. Tomatoes are intentionally delivered to grocery stores unripe to reduce shrink. Unripe fruit is more durable and less inclined to damage in transit. In addition, the grading system the USDA and all retail outlets use to judge the quality of fruit ironically does not include flavor as a factor.
Consumers can do a couple of things to maximize the flavor though. First, never refrigerate tomatoes. The chemical we associate with a good-tasting tomato is cold averse, and storing tomatoes in temperatures below 55 degrees gives them that unpalatable mealy texture. Also, trust your nose. You can get a pretty good idea of produce flavor in the store by smelling the blossom end of the tomato (and most melons for that matter).