The word "sweet" has connotations of sugariness, kitsch and even blandness. Comparing this to the word as it was used in the past, that can't have been its original meaning. For instance, the author of psalm 119 writes (about the divine law) "How sweet are your words to my taste sweeter than honey to my mouth!" Yet the psalmist writes a bit further on "My flesh trembles in fear of you; I stand in awe of your laws." So not sweetness in the Hello Kitty sense. Perhaps we've lost the meaning of the word sweet by eating to much sweet stuff, especially food in which refined sugar is used. As Shakespeare said "…sweets grown common lose their dear delight."
Our household decided to ban all refined sugar about 2 years ago. We drink only water, milk, tea, and - very rarely - freshly pressed unsweetened orange or lemon juice. We don't have deserts. We do eat fruit, obviously. (My daughter compensates by having lots of ice cream and candy when we go out or visit other people). So I consume a lot less refined sugar than I used to. One thing I began to notice after banning refined sugar is, paradoxically, how sweet things can taste. A ripe strawberry or a date in one's mouth is a bomb of sweetness. I can't imagine now that I used to add sugar to fruit salads! And when I do eat sugar (such as a desert in a restaurant) it is very, very sweet - sometimes too sweet. Perhaps this phenomenological experience captures the semantics of the word "sweet" used in a metaphorical sense better. So sweet used in the original sense is perhaps less cute and more overwhelming.
I used Google nGrams - which charts the relative frequency of words in a large corpus of English fiction - to compare the changes in word frequency in "sweet", "sour", "bitter" and "salt" (umami, the fifth taste for which we have receptors, was only used in such low frequency, and only so recently began to be used, that I did not include it). I found that the frequency of the word "sweet" increased dramatically around the turn of the 18th century, which is in line with the mass production of sugar from beets and cane that accompanied the Industrial Revolution. Comparing this with other words for tastes the pattern is quite distinct. Salt consumption also increased as a result of the industrial revolution, but this is not reflected to the same extent as the increase in the word "sweet".