I don't think there's any mystery.
Hank's musical roots - he's said so many times - were in jazz and blues, and his instruments were initially piano and banjo. His duffle coat period would have been recognised by the Ban the Bomb generation (I've always been partial to duffle coats myself, and still have one).
But Hank's career took over in the late fifties and travelled in a divergent direction. For those of us whose musical preferences first centred on The Shadows sound (and there are hundreds of thousands of us all over the world), it's our loss. But Hank's gain!
Best wishes,
JN