I have observed a trend in punctuation over the last ten years of increasing usage of exclamation marks. I believe this is because our culture has shifted to feel that full stops convey seriousness or even anger, while exclamation marks convey excitement, enthusiasm and cheerfulness.

An effect similar to the euphemism treadmill has lead to a state where exclamation marks are becoming the most common way to end a simple sentence.

Does this mean that the roles of full stops and exclamation marks are being reversed in casual writing?