It's hard to be surprised at this; he was not young and his health problems were well documented. And it's not like he's done comics in decades; or anything that I'm aware of in years.
That doesn't stop this from hitting hard for somebody I've never met. His paintings are so classic and defining that I literally cannot imagine what the world would be like if Frazetta hadn't existed: He influenced everybody who came afterword. ...
I think you summed up my sentiments exactly Eric.
Although my comic collecting days began in the mid 70s... perhaps a little more than a decade removed from Frazetta's most prolific and greatest artistic flourish (and certainly a generation or two removed from his comic book work)... I still feel a great sense of loss after hearing of the passing of this unique and major talent.
But I guess it's unavoidable. His work, in one way or another, inspired (and to a great extent infused) a whole generation of artists from that period, leaving an indelible stylistic impression on them, the fantasy genre in particular and indirectly, the whole of comic-dom... even to this day. It wouldn't be an overstatement IMO to consider him the da Vinci of his day (at least within the confines of the fantasy sub genre).
RIP Frank.