When someone describes something as 'terrific' do you assume they mean it sarcastically?
I wonder if it would be possible to study the use of the word across the Internet and measure the ratio of how often it is used in earnest versus how often it is uttered with sarcasm. It might be difficult to quantify, given that sarcasm is usually indicated by tone of voice or some sort of physical gesture or facial expression, but certainly there are instances where even in writing the context is obvious. This seems like something Google should figure out how to do.
My guess is that the data would show that over the years--with the real shift beginning in, let's say, the mid 1980s after which it seems (to this child of the 80s) all the innocence began to leech out of the world--words like 'terrific', 'great', and 'wonderful' have become increasingly used in a sarcastic context rather than with the intent of expressing genuine delight.
More old-fashioned sounding words, like 'splendid' and 'grand', seem to be reserved for the highest pronouncements of mock-enjoyment.
We have a great many words in English to describe things with extreme positivity: Marvelous! Awesome! Sensational! Stupendous! First-rate! Fantastic! Excellent! Superb! I see them all splashed across the page in colorful, bubbly fonts surrounded by clipart of smiley pencils and party hats like the stickers my kindergarten teacher would put at the top of little stories I wrote when I was too young to get actual grades on things. But when I read these words, I rarely hear that exclamation point. Now I hear a deadpan period.
Are we just more negative, more complainy as a culture than before? Are we simply less easily impressed in a time when 'innovation' in the form of a monthly parade of new and mostly-useless gadgets vies for our esteem and attention? I don't know. When was the last time you felt moved to call something 'stupendous!' in earnest?
This reminds me of a Don DeLillo quote:
"He'd once told me that the art of getting ahead in New York was based on learning how to express dissatisfaction in an interesting way. The air was full of rage and complaint. People had no tolerance for your particular hardship unless you knew how to entertain them with it."
Maybe that explains what's going on. Language evolves; words come in and out of style and change meaning over time. Take 'sentimental', once meant in a more positive way as 'of or prompted by feelings of tenderness, sadness, or nostalgia', like in Sam Cooke's song, "I Love You For Sentimental Reasons". The modern connotation of the word seems to have a negative sense of being 'overemotional, self-indulgent, mawkish', like in the Radiohead song, "Let Down": "don't get sentimental / it always ends up drivel".
So our superlatives are evolving. No longer needed in the service of describing how great things are, people are creatively repurposing them for expressing just how superlatively shitty everything is.