Frozen is good for smoothies / shakes. You cannot put fresh berries in a mixer and get a smoothie back, instead you'll get an expensive lump of thick substance that you cannot push through the straw :)

The same process makes certain things difficult or impossible because the frozen fruits and vegetables will fall apart (quickly) when cooked.

Also, I will prefer frozen spinach to fresh any day because it takes less time to cook (you can measure enough of it right away into the pan instead of adding incrementally and waiting for it to whittle and cook down).

Also, I think all these compliments to fresh locally picked food vs the plainest cheap stuff from the supermarket exaggerate the difference... a lot. Sometimes there's indeed a noticeable difference because a particular sort of fruit or veg aren't grown industrially (eg. there are plenty of sorts of potatoes but in a supermarket you will find maybe two, which are probably the most resilient to pests). But if you were to grow the same sort of potato you buy from supermarket, I'm pretty sure the difference would be so small as not to be noticeable at all.

From what I understand, if you freeze anything quickly as opposed to slowly, the resulting ice crystals are much smaller -and they tend to have much better taste and texture.