So the death of Captain America - when his resurrection was a forgone conclusion, considering he's a Marvel flagship character - and bringing back his sidekick were both more important than the unnecessary death of one of the ONLY women in the Cap mythos, who's been around in some capacity for nearly fifty years? That's the Marvel line?
Your argument might carry a little bit more weight here if Sharon hadn’t previously been dead for close to half of those fifty years. She’s not an unimportant character, but she’s been dead before, for decades, and CAPTAIN AMERICA went along just fine.