The "why don't we find a body?" argument is deeply illogical, I believe, on two accords.
1) I was extremely fortunate to join with a wilderness S&R team for several years. In that time, I was on several searches that involved one missing human with limiting factors on their mobility (age, under the influence) whose last known point was well defined (e.g., a bar, an abandoned car in the woods, a small regional park). Even though most of our searches (in downstate New York) don't involve "wilderness," I was on two searches where people weren't recovered until months after they had disappeared despite extensive previous searches. The remains of a drunk teenager weren't recovered until months after he had disappeared in a search area less than 1 square mile, 75% of which was dense suburbs. In another case the remains of a man were recovered less than a quarter-mile from the State Park parking lot. In both cases, terrain and weather (snowfall) hid the body for months. Prior to my joining the team, they were involved in searches - again, in a relatively limited area - where remains have never been recovered. It's just not as easy to find what is at best a full human body in the woods.
2) What do wounded animals (including humans) do? My understanding of wildlife behavior is that wounded animals find the most secluded spot they can and attempt to burrow in. It took four days to find and rescue a man w/medical issues who had burrowed in (or just gotten weak and couldn't go any further) in a search that was covering less than 2 square miles in a suburban area of lower New York. I see no reason why Bigfoot would react any differently. Unless one is hit head on by a truck or a train, its going to limp as deep into the woods as it can.
I agree that the lack of a body is a problem, I don't know if it rises to the level of suspicious.