The main target of fast-check has always been to find bugs without too much help of the testers. Instead of forcing you to think about the possible things that can go wrong, fast-check asks you to explain what to expect from your algorithms and it should find what goes wrong for you.
As such, the more fast-check thinks about nasty things, the higher the chance to detect bugs that may happen in production before you.
Since version 3.0.0, we have started to push more and more for defaults enabling everything. For instance, double not only generates classical numerical values but also infinities, not-a-number or negative zero.
This new release goes in the same direction, by preparing the ground for version 4.0.0 to enable even more defaults immediately. So far they are opt-ins while they will be opt-outs starting in the next major.