Playing a game shouldn't require a maths degree to understand what's happening, at least for something you do virtually every turn like combat. User interfaces in general should adhere to the "Principle of Least Astonishment":
http://en.wikipedia.org/wiki/Principle_of_least_astonishment
... and astonishment is a pretty good word for how many people feel about these unlikely outcomes. Taking some of the rough edges off the uncertainty like they did in 5 makes a slicker game experience and loses zero game depth. Perhaps even adds some tactical depth.
Not saying there shouldn't be a ton of low-level maths in the game that experts and number lovers can delve into of course. All that stuff's great so long as the general principles are obvious, e.g. build a library and it's generally a good for your tech, or whatever.