Another reason to include sweets in your diet:
I'm afraid this remains to be shown.
Sorry to be such a nitpicker, but the relationship could well be in the opposite direction (perhaps we should all be a bit grumpier, thereby reducing our risk of caries and type 2 diabetes
) or due to a third variable that causes both.
The studies about the (causal) effect of consuming sweets have only looked at the short term.
The studies about dispositions have only looked at the correlation stable preferences and personality traits and they have controlled for influences of mood and recent consumption thereby making it unlikely that the relationship is due to the aforementioned short-term effects.
Interesting topic, though.
Though I find the popular conceptions about personality and taste even more interesting than the actual correlations.