It really depends on how you play. A lot of people will get upset if they lose the ability to finish their world from a single death, and it's especially bad if you have a laggy computer or the Minecraft version you're playing on has a lot of bugs; then you might die entirely unfairly and not from an actual interesting reason.

Some people may prefer hardcore, and some may prefer traditional survival. I'm not counting Creative here as it's an entirely different paradigm, of course.

It's something to be proud of if you build something big over a long period of time in Hardcore mode, and you won't lose it just because you die as you would load in in spectator mode, and be able to see it without editing it. (you need to enable the gamerule for spectators loading chunks though)