I don't recall the precise number for probability of winning (and Twitter chat doesn't have search) but your simulation is kind of in line with our expectations. We didn't put anything on probability into the SRD, but perhaps we could.
It's also worth noting that there some W&A games that have toyed with making things easier and creating more winnable experiences as there are definitely experiences that make sense within W&A that have more positive outcomes.
We do already have some plans for a 2.0 SRD that addresses a few things about the current version, but those plans haven't been able to move forward quite as quickly as we would have liked.