>It seems dragons are without exception in Western literature depicted
>as lazy, unambitious creatures, sleeping for centuries, avoiding
>physical exertion, and only rousing themselves to great and terrible
>purpose when some pesky adventurer comes along and sneaks off with the
>+5 Holy Mace "Peace Thru Repeated Thwappings" from their treasure
That ain't true, at least in modern times.
The most famous dragon in Western literature is probably either Smaug or St. George's dragon. The St. George legends are... weird and atypical, so let's talk Smaug.
Smaug was neither lazy nor unambitious; he singlehandedly took on a powerful dwarven kingdom that was allied with a powerful human kingdom, in a universe where both dwarves and humans often slew dragons, sometimes single-handedly. And he did it only to obtain glory and wealth for himself.
It's true that after the deed was done, he took it easy for a century or so. But, you know, he'd won.
Tolkien's other big famous dragons, Glaurung and Ancalagon, can't really be said to have been all that lazy and unambitious either.
So that's at least a few exceptions, and I'd argue that all the people who wrote about dragons following Tolkien used the same model. Dragons don't obtain treasure hoards by being passive, indolent creatures; they gain them by murdering lots of people with fire/acid/what-have-you and taking their shit.