Wilson is better than anyone the Steelers had last year, which goes without saying. So the benefit of the move is intuitive.
but…
If he busts, and the fans then have to suffer while the Steelers figure out why the Bears dumped Fields, well then it was a predictable error.
In summary, based on what we have seen of them, the possibility that Wilson plays well is higher than the likelihood that Fields will be a much better replacement.