I also think ripeness is a huge factor. When you think about it raspberries are always picked and used very ripe, they're either ripe or not. Peaches and strawberries often get picked underipe. The time between perfectly ripe and moldy is very short, sometimes 1 day. I get great peach flavor in mead using my own fresh picked ripe peaches (usually picked ripe and immediately frozen before using, actually). I know there is a chemical component to ripeness. Maybe its partly because most don't use very ripe fruit that the flavor doesn't come through.