I loved Body Wars as a kid - in fact I much preferred it to Star Tours 1.0 - though a big part of that was likely my interest in anatomy-related science.
That said, while it would feel long-in-the-tooth today (much like Star Tours 1.0), much of its lack of popularity was likely the result of its location.
If, instead of closing Wonders of Life, they'd just turned the pavilion into "Body Wars" (with the main dome being part of the queue), I think it would've remained popular enough to have been useful for park capacity.