I would not call the show a complete failure, but it was very evident that the show was shot during a period of studio in-fighting. Plus, it just was not the same Boba Fett that fans saw in season 2 of Mando, which is what fans wanted to see. 

The show was originally written by Jon Favreau and he was originally told that he would have autonomy to develop it apart from Kathleen Kennedy’s Star Wars projects. That deal changed while filming Book of Boba Fett. That is why the story appeared to bounce in completely different directions at times. Entire plot points were changed by studio executives and filmed behind Favreau’s back. By the time Favreau discovered what was happening, he did not have time or money to reshot the whole series again, so he cut a lot of scenes and replaced it with scenes he intended to use for the Mandalorian show. That is why there were two episodes of Boba Fett’s show that did not really include Fett and featured the Mandalorian instead. Favreau then just reshot the final episode. Overall, the show turned into a cobbled together story, which caused the viewership to drop off from week to week. 

Actually, Nick Fury did have an inferior version of the super soldier serum. While It was not as good as the version Steve Rogers had, but it did slow down Fury’s aging and gave him a physical buff. Fury is around 100 years old and still going toe-to-toe with superhuman opponents.

In the case of Forge, it seems like it should be obvious why he would leave his leg exposed. His super power is to break down technology and rebuild it into any form he can imagine. Having his leg uncovered would make it easier for him to make changes to it on the fly. He could also provide him with easy access to parts, for building new tools in the field. Need to power tool for dismantling a computer? He could repurpose parts from thigh.