Its popularity relative to steampunk is really a special case of a perplexing general popularity. I really don't want to compare the two but despite all the insistence that steampunk is distinct from cyberpunk mentioning the latter invariably prompts discussion of the former. Asserting its superiority is in many ways akin to asserting Earths superiority to the Solar system: Earth is unquestionably the part of the system most noticeable and relevant to the speaker, but remains a part and product of it whether or not the speaker chooses to acknowledge those facts, and would perish quickly if separated from the systems unique characteristics.

The other problem with trying to make less than the sum of the parts greater than the whole is the much lauded aesthetic. I expected objections to describing it as noir, since current steampunk is often less so than early steampunk, and because, as I noted in my appendix on steampunk, the "gritty", "edgy" and "PUNK" aspects of steampunk are as anachronistic in the Victorian Age as the prosthetic augmentations so common in steampunk. That part of the aesthetic is purely postmodern; it works in The Maltese Falcon, it works in Reservoir Dogs, it even works in a book by K.W. Jeter (the steampunk author who named the genre)--but his novel is science fiction, not steampunk; it's a lot closer to cyberpunk, in fact. Punk was a seventies phenomenon, and so an obvious anachronism in the Victorian Age, but since you're in a good position to say: Is Victorian postmodernism a viable concept?

To put it bluntly, I don't want to get into a pissing contest, because no one can win if everyone has to share equipment. HOWEVER, if we must go there, retaining superficial cyberpunk elements completely anachronistic in the Victorian Age while stripping away any substantive element that gave cyberpunk (or gives steampunk) status as more than a trendy fad makes steampunk hollow. Where steampunk retains substance and doesn't blithely ignore science to look cool I respect and enjoy it, but where it does the opposite I can only stare dumbfounded when its acolytes call the parent genre "dated" or "the definition of trying too hard".

I don't think its important themes have bled out into general SF, because the biggest is how technology (computers especially) affect mens understanding of themselves and relationships with others, long been present in SF. Cyberpunks specific focus is on imminent technologies and effects WE (not distant interstellar descendants centuries from now) must soon confront. Steampunk can do that quite well with alternate histories where technically viable but undeveloped science IS developed, even hybrid human machine consciousness. I'd enjoy a well written convincing story of a Druid integrated with Stonehenge in the Fifth Century BC on many of the same levels, though it wouldn't offer cyberpunks near future promises because I know it didn't happen, even if it might have been (or be) possible. Still, I can't shake the suspicion that some of steampunks greater popularity is reactionary, that people prefer to pound the square peg of the Information Age into the round hole of Victorian Britain because it's safely remote in history, where we know it didn't--COULDN'T--happen, so they can ignore imminent realities too chilling to confront. Not that that makes any of them disappear.

To summarize, since I run long, my main point is that cyberpunk is under-appreciated critically, given its ongoing relevance. I believe the CAUSE is that it's perceived as stale, which is ironic when contrasted with the great popularity of a derivative deliberately "dated" to a century ago. I am not saying steampunk is less worthwhile or deep than cyberpunk, because I AM saying it is an aspect of cyberpunk, and because it can be every bit as deep and worthwhile; it's disappointing to see its ardent fans almost forbidding it do so.