The Democratic Party's nominating process, with superdelegates, is unfair and undemocratic. Superdelegates should not have so much more say than the average citizen. Having said that, Bernie Sanders did not lose because of the unfair superdelegate system; he would have lost anyway because he lost the popular vote to Hillary Clinton.
The presidential nominating process should be changed because as it stands now a person's vote can be cast aside by the whims of delegates. There is too much room for political maneuvering to nominate a certain person, rather than nominating the person that the people voted for. Rules should be consistent across parties.
Many voters feel like the Democratic Party's nominating process was rigged by super delegates. Super delegates are not bound by elections; instead, they can pick any candidate they want. The vast majority of super delegates picked Hillary Clinton from the beginning and didn't care how their states voted. This gives the appearance that the Democratic Party denied Bernie Sanders a chance at winning the nomination.
Bernie Sanders was not derailed at all. Hillary Clinton is just a formidable opponent. If several parameters were changed, such as, the removal of super delegates, she would still win. If you looked only at the electoral votes, she wins that too. He ran an amazing grass roots campaign that he should be proud of but he was beaten fair and square.