Why has Hawaiian downsized their planes on flights especially since it is so difficult to capture award travel at current time and even in the year to come?

they haven't downsized, the dc9 and the 717 are virtually the same plane except one is make in the 70s/80s and one is made in the 00's
Jason

The HA inter-island fleet is currently, 15 DC-9-50 with 8F and 125Y config. They will be accepting starting Feb 2001, 13 B717-200 with 8F and 115Y config. The DC-9-50 will be retired.

So the nice basic bottom line is fewer planes and each plane will have fewer seats. Hopefully the improved reliability will make up for any differences.