Comparing Smith to Kinnick isn't quite fair. While Smith served his country honorably during WWII, Kinnick was killed in a training mission off the coast of Venezuela in 1943. Kinnick even has a Japanese high school named for him (for children of US military personnel). A quick look around shows that (perhaps not surprisingly) Heisman trophy winner statues are mostly found in the South and it is a more recent phenomenon. None of the Notre Dame (7 recipients), Ohio State (7) or Michigan (3) Heisman winners have statues (although Paul Horning does have a statue in his hometown of Louisville, but that honors him more as a footballer in general). Notre Dame does have statues of their 5 national championship coaches around the stadium, including Lou Holtz!
What might be nice in the stadium would be to somehow recognize Smith's achievement via a plaque, display case, etc.