The main reason she lost is the electoral college. Based on that system, each state gets a certain number of votes. Since we are a republic of states united, the framers wanted to make sure the population centers didnt take over every election and that all states had a vote/say in governance.
And yes, its a good system, unless a certain party looses then they think its horrible

State elections (governors, senators and representatives) are done by popular vote and the president is done by "States Vote".
For illustration, lets say you had 1 huge state and 9 smaller ones. Lets say the huge state votes for candidate A and the 9 smaller states vote for Candidate B. How fair is it for every presidential election to be decided by the huge state? So, if the big state has 10 Electoral votes and 8 of the small states have 1 vote each and the last small state has 3 electoral votes. That means that Candidate A won 10 electoral votes and and candidate B won 11. Candidate B wins.
One could extrapolate that Candidate A only resonates with 1 specific demographic, while candidate B is preferred by a more diverse set of the population since different states have different needs or candidate A would have won more of the electorate.
Remember...
You can sheer a sheep many times, but only skin it once!