Good question. Usually when the incumbent president is not running for 2nd term, more candidates throw hats in the ring. But why 17 this time? Good question.
If it was only 17 this time it would be a blessing. Take a look at this FEC Form 2 filers.
Now granted most won’t be a factor but in some places they may could get a vote or two.
http://www.fec.gov/press/resources/2016presidential_form2dt.shtml