Blake is an outstandingly impressive runner, and is welcome to run how she pleases, which she does.
However it was a terrible and not very useful tactic. She set up the other runners and burned herself out.
Generally runners go out at an excessively fast pace because of two reasons:
1) Insecurity, fear of being able to win (or place) thus putting on a show of leading for 15 or 25 miles. But the race was 26.2188 miles. Whoever leads before the final parts of the race is of no consequence.
2) Overconfidence, and lack of respect and consideration for the abilities of the other runners.
Reading the race recap, my feeling from the start was not that she was brave, but that she didn't deserve to win the race, nor to place.
However, ability wise, she was certainly in a position to have won, had she run the race well.