I think the F-16 over the years has suffered from mission creep, that has added weight and decreased performance.
Then again, thinking about this, the USAF really plans on logistics, and most of the plans I've seen really focus on how plans can carrying something (usually bombs) to a place, from far away, and flying around enemy radar and other badness. They really need the equivalent of a fedex truck that can't be shot down.
Yes, the F-16's performance has suffered greatly as it's become more "multi-mission."
Ironically, the philosophy for the F-15 was "not a pound for air to ground" yet both it and the F-14 (in its F-14D Bombcat config) turned out to be exceptional tactical bombers. The F-16 isn't bad, but because of the small wing has far less range than the Mudhen or the F-35.
Then again, thinking about this, the USAF really plans on logistics, and most of the plans I've seen really focus on how plans can carrying something (usually bombs) to a place, from far away, and flying around enemy radar and other badness. They really need the equivalent of a fedex truck that can't be shot down.