Kaley Cuoco's Penny would have been unusable if The Big Bang Theory stuck with its original setting. It's no secret that the first The Big Bang Theory pilot was reworked quite heavily. While Jim Parsons' Sheldon and Johnny Galecki's Leonard pretty much stayed the same, the rest of the cast was replaced. Amanda Walsh's worldlier and ruder Katie was scrapped and Cuoco's kinder and nicer Penny was brought in. Meanwhile, Iris Bahr's Gilda was gender-swapped and split into Simon Helberg's Howard and Kunal Nayyar's Raj, rounding up the initial five-person roster of the Pasadena gang.
In its first three years, The Big Bang Theory leaned on its original cast. It eventually expanded with the addition of Amy and Bernadette as series regulars in season 4, but before them, Penny was the only main character on the show. This resulted in some narrative issues that even people involved in the project regret now. That includes objectifying and sexualizing Cuoco's character, not to mention also boxing her in the dumb blonde stereotype, which juxtaposed with the rest of the cast who were scientists. Despite this, it's difficult to imagine The Big Bang Theory working without Penny — something that could have happened if the show didn't change locations.
Over the years, the original The Big Bang Theory pilot was discussed multiple times. The entirety of the episode cannot be found online, but bits and pieces from it have been shared on social media, allowing fans to check them out for themselves. The recasting for its lead female role and the addition of Howard and Simon have been the most impactful changes made to the show, but apparently, there were some lesser-known alterations done to it. In a new interview, Parsons reveals that The Big Bang Theory was supposed to take place on the East Coast.
Admittedly sitcom barely had any exterior scenes, and although it was filmed in the Warner Bros. lot in Burbank, the cast shot most of the series inside a sound stage. They could have easily faked an East Coast location — something that countless shows have done in the past such as Friends and Brooklyn Nine-Nine. That being said, while it may not sound as significant compared to all the other revisions done, it's difficult to imagine The Big Bang Theory not taking place in Los Angeles, with the cast not being in Pasadena. All four main male characters on the show, as well as Amy worked at Caltech.
Parsons doesn't reveal where exactly on the East Coast The Big Bang Theory was supposed to be set in before its original pilot was revamped. That being said, since the show was grounded in reality, albeit with some fantastical elements, it's possible that co-creators Chuck Lorre and Bill Prady were planning to set it around Massachusetts where both Harvard and MIT are located. This automatically means several changes, particularly to Sheldon, who liked mocking both institutions. He particularly poked fun at MIT because it's Howard's alma mater, and he hated him for being an engineer — as he explained in Young Sheldon.
More than that, however, setting TBBT in Massachusetts, or even Boston would make introducing Cuoco's Penny impossible. In the sitcom, she moved to Los Angeles to be an actress. Although she never became one as she was eventually forced to give up on her dream, it was a big part of her arc in The Big Bang Theory. New England as a whole is far from an entertainment hub, making it impossible to justify Penny's move to Massachusetts as an aspiring actress. New York could have worked in this regard, but Columbia and New York University just don't have the same name recognition when it comes to the boys' fields.
Penny was underserved in The Big Bang Theory. Howard harassed her while Sheldon mocked her and her intelligence mercilessly. Despite their treatment of her, the sitcom would have likely failed if it wasn't for her. The fact that the show finally clicked once Cuoco was brought in to replace Walsh's Katie is proof of that. Penny was kind and understanding but only to an extent, which meant that she wasn't a pushover, resulting in an interesting dynamic between her and the boys. She was the viewer's point-of-view in The Big Bang Theory and her outlook on the social outcasts made it easy for comedy to endear them to the public.