I believe that Hillary Clinton should own up to her mistakes because she is running for the highest office in the land. Americans want their politicians to be honest. For Mrs. Clinton honesty should be the best policy if she wants to be seen as different from her Republican competition. Being honest about her mistakes will also give her credit by showing that she is a human being who can own her mistakes.
Clinton has said on numerous occasions that made a mistake using an unsecured server, but that hasn't been good enough for everyone. She has never denied using the server, and has made it clear, and been backed up by the investigation, that at the time none of the information was deemed confidential.
I tend to agree that her reaction to getting caught was horrible by refusing to answer questions , turn over emails, and lie by saying others did the same and she had permission, telling us the FBI investigation was a "routine security review" , etc. When Bill Clinton was exposed as having an affair in the WH, the lying under oath to Congress was worse than the crime. It appears she felt she was above the law and was immune because she is a former first lady and current candidate for president.
Why should she? The best politicians always lie, it is how they get things done. Quite frankly I would be a bit disappointed if she did own it. A politician is supposed to be slimy and weaselly. She is just living up to her full potential. She's good at it