As anyone who has a TV, listens to the radio, or reads Websnark knows, Captain America is dead. At least for a little while. Comic death, especially super hero comic death, is a bit more negotiable than the genuine article. See Superman. Or Hal Jordan. Or even Reed Richards and Colossus.
This is less true in webcomics.
Sure the Tycho and Gabe kill each other regularly over at Penny Arcade, and that's pretty mutable, but in other comics, especially ones with dramatic arcs, death is a bit more final. It is unlikely Davan's mom is going to come back from the grave. Johnny Saturn is dead when he is introduced to us. Alternate world Zoey is pretty dead too. Seigfried is still dead, if still kicking about hell. Deaths in webcomics are usually supported by the fandom, and critically well thought off. They have meaning. There are fans of superhero comics, on the other hand, that would have them emulate comics on the web, or stay away from hero death altogether.
A good portion of the fandom is really upset about killing off the Cap, and some of that is just fan mourning. After all, when your hero gets killed, or even does something stupid, you get upset. People felt this way about Seigfried or the dog from For Better or for Worse too.
But other people have pretty much accused Marvel of pimping out their properties for a cheap short term buck at the cost of their legacies. I don't think that's fair. Yes, Marvel is hoping to cash in on this event, and yes I am sure the timing at the end of Civil War was as much about commerce as it was about dramatic effect (though I do think it was dramatic). A bigger reason things like this happen is that there are real weaknesses in the superhero genre itself, and those weakness force these kind of events to occur. As I see it, superhero comics fail to have meaningful deaths because they are are not creator owned/controlled, they have continuity shackles, and they started out as childrens pop culture artifacts, causing them to suffer with the growth of audience sophistication.
Creator ownership means that the creator of a character or set of characters are at the mercy not of a corporate bottom line, or a rotating set of editors, or a rogue hot writer, but just one man, the man that birthed them. When a creator kills off one of his babies, he has a damn good reason. When a guest writer kills someone off, it may just be for excitements sake, or becasuse he wantsa to explore something entirely foriegn to what the creator envisioned. And then the next guy may decide he wants to change it back. Or the owners may not care about vision but rather want to shake things up. In any event, most webcomics are creator owned, and most superhero comics are not. So death is going to be different. And less permanent.
The second and deeper problem is that superheros really exist in their core as an entertainment for children and young adults, and not just all children and young adults but mass audiences of children and young adults living in the 1930's to 1960's. That audience is gone. The people who read them are adults now, and the children and young adults who could read them are more sophisticated than and have more options than the kids they were originally written to target. This means that the sort of stories that they used to tell, even if fondly remembered by many long time readers, just aren't going to hold up. Adults without the light of nostalgia won't be interested. Kids will read manga that targets there interests. Superhero comics stories have to change. Become more sophisticated. And the truth is the with their extensive, long running continuity, fan investment, and grinding pamphlet a month pace sophistication there is going to be meaningless deaths. The comics can't get away from it. With a fixed set of characters with pretty much immutable personalities, their are few stories that can be covered. And story arcs that appear to have import are going to have a premium because the audience needs the sophistication. Story arcs that involve death or other appearance of serious change come at the top there. And in the long run it won't help because its not sophistication, but a veneer of sophistication.
As for solutions, I am not really sure. It is easy to see how superhero comics are one way with regards to death and webcomics (or really all independant comics) another, but implementing changes to give them webcomic's flexibility would be hard. Comic companies would have to be willing to give writers longer positions and editors more control, and share holders less. They would have to ease up on the contiuty demands that force ridiculous rebirths, and allow more one shot comic series involving the heros. And they would need to learn to reengage the youth market. And that means changing characters that the companies can't afford to change in the short run. I am not sure those things can happen. But don't blame Marvel for killing Captain America. It's the nature of the beast.