Secretly, The Big Bang Theory finale failed Sheldon's (Jim Parsons) true soulmate. The CBS sitcom premiered in 2007 and became one of the most popular comedies of all time, ultimately running for 12 seasons. Considering its success, The Big Bang Theory could have continued much longer as the network was interested in renewing it for two more years. However, Parsons' decision to exit the show convinced everyone else that it was better to wrap up the project altogether than continue with an incomplete cast.
Because of its fairly abrupt ending, The Big Bang Theory final season was uneven. The show introduced certain plotlines that felt like they were supposed to play for far longer, particularly Leonard (Johnny Galecki) and Penny's (Kaley Cuoco) pregnancy conflict. Meanwhile, Raj's (Kunal Nayyar) romantic plot ultimately didn't go anywhere. The only narrative that was well-crafted in the final season was Sheldon and Amy's (Mayim Bialik) bid for the Nobel Prize in Physics, which they won in the end. It was the pinnacle of the Sheldon Cooper's arc, as it was an accolade that he had long dreamed of.
While it was great to see Sheldon win the Nobel Prize in Physics with his wife, it actually undermines the character's real soulmate — Leonard. The Big Bang Theory was an ensemble show, as it focused on each member of the Pasadena gang, but its core relationship was always between the boys of Apartment 4A. Since the Nobel Prize category that Sheldon won was in Physics, it makes more sense that Sheldon and Leonard would have been the ones to team up for the Super Asymmetry study. The fact that Leonard is an experimental physicist compliments Sheldon's field of specializing in theoretical physics. By contrast, Amy's specialty as a neuroscientist made less sense for the collaboration. It would have been more touching to see Sheldon and Leonard work closely together on a project — something that they hadn't done in a long time, and eventually succeed in their endeavor.
Sheldon and Leonard were the only characters from the original pilot of The Big Bang Theory who were retained when it was reworked, which means that the creators intended that the overall series' story hinged on their relationship. Leonard had been Sheldon's closest confidante long before Amy came. He took care of the genius, tolerated his quirks, and even shared his friends with his roommate. All the social connections that Sheldon has eventually had stemmed from his friendship with Leonard. Seeing The Big Bang Theory ending with the success of Leonard and Sheldon would've better wrapped up the sitcom. It would've brought the characters' collective arc full circle since it started with the pair struggling to get their career going, even resorting to donating to a sperm bank to earn some extra cash.
There isn't any inherently wrong with Sheldon winning the Nobel Prize in Physics with Amy. After all, they are a couple and his life really turned around when they met. However, The Big Bang Theory finale could have been so much more satisfying if it really leaned on nostalgia and brought the focus back on its two primary characters. This would have been especially nice since Sheldon and Leonard hadn't really had the time to bond one-on-one in the show's last few seasons.