WRP never lived up to its potential. As Mythbusters proved over the years, Kari, Grant, and Tory had some great on-air chemistry and creative genius. Unfortunately those assets failed to translate to the new format which suffered some fatal flaws.
WRP was clearly a spin-off of Mythbusters, but it took worst aspects of the show — poorly contrived dialogue and setups — while also failing to put the hero of the series — its over-the-top, novel builds — front and center.
If WRP were given one or two more seasons, it probably could have found its feet and been successful in its own right. The first couple seasons of Mythbusters were also clumsy before arriving at a formula that eventually worked. I wonder, though, if its hosts were just ready to move on to new chapters in their lives, separate from the orbit of Mythbusters that had defined so many years of their lives.