The Big Bang Theory isn't a particularly complicated show. It's a story of four socially inept friends that try to navigate life, each with his unique idiosyncrasies and a desire to pursue the ladies (although Raj might not desire women and Sheldon might not desire anyone). They are nerds, a popular stereotype in television, but this is not your classic nerd-gets-hottie story. Instead, it's just about a group of guys that happen to be really smart.
So, with that description, the show does not sound remarkable. Yet, it genuinely pulls in almost as many viewers as the legendary Friends in its prime, so there has to be something deeper there, right? Actually, there really isn't.
Big Bang started off kind of unique. Whereas stories revolving around nerds are often meant to evoke sympathy, they ultimately work only to mock the characters. Be it Steve Urkel or anyone in Freaks and Geeks, these were people no one wanted to be. However, Chuck Lorre's show was not about that.
Instead, the comedy just showed us what these nerds do in a very sincere manner, without ever expecting us to feel bad for them or relate to them. When Sheldon and Leonard sit around discussing what exactly is the problem with teleportation, it isn't meant to evoke a simple laugh or the traditional "aw" that audiences love to give when they see a nerd stumble. Instead, it merely caused the viewer to go "WTF?"
So instead of making us suffer another Nerd Meets World, the author showed us nerds in their own world.
And in that sense, it really was a niche show at the start, albeit a hilarious one. When the greatest problem our unassailable geniuses are facing is who will keep the Sword of Azaroth or whether Superman flying into Lois Lane would actually slice her in half or not, most people probably would not be able to relate with them and certainly would have no reason to sympathize. Those following the quick dialogue would see the humor but, for the most part, there was nothing making them "normal."
However, as time went on, the show changed. The issues became something everyone could see. In Sheldon, there is the annoying friend who thinks he's so much smarter because he knows the original function of the appendix. In Raj, there is the friend who's kind of a jerk when you think about it. In Wolowitz, there is the guy who can't stop hitting on women, no matter how much he sucks at it. And in Leonard, more so than anyone else, we see the guy struggling to get the girl, something that is much more familiar territory.
They are still nerds, something we see in their love for comic books and all things sci-fi, but the issues aren't about that anymore. When Wil Wheaton comes to visit Sheldon and the thing we're focusing on is girl trouble with Amy, it's clearly something beyond the focal span of a true nerd when in the presence of a Star Trek cast member.
And maybe that's why the show doesn't inspire deep conversations the way some comedies do, because it doesn't do anything deeper. There are women in science, but it does not highlight the trouble women have in being respected academically. It has a brown guy, but he's no slumdog millionaire (his dad's a gynecologist, for crying out loud; he drives a Bentley) and the show is not about him being brown. It has a strictly atheistic man with a devoutly religious mother, but there are no gigantic confrontations or contemplations of faith in science.
The show also does not make seamless shifts into darkness like Wilfred. It is not edgy and offensive like Shameless, Louie, or Curb Your Enthusiasm. And it does not define a generation like Seinfeld or Friends. Therefore, it makes sense that the show does not inspire serious discussion like any of these comedies. So, why then does it get more views than almost all of them?
By being just funny.
The Big Bang Theory may be regressive comedy, because it really doesn't guarantee anything more than laughs, but it doesn't really need to either. At its core, comedies should promise us, first and foremost, laughter; the show delivers that in spades. Viewers will memorize the quotes and laugh every time they hear them, but they will probably never need to think anything more about them.
It's not a show that will make you talk about the meaning of life or the diversification of America, but it will give you hours of funny jokes that you can just quote in forums and inspire raucous laughter; at the end of the day, that is the first thing comedy needs.