With the sudden success of any intellectual property, there will always be objectors and contrarians to tell the masses why they are wrong for loving the things they love. Some folks are quick to see the monetization of the things they once loved is an act of aggression against their own value. The irony is that most "geeky" properties that aren't cranking out billion dollar films would love nothing more than to be brought to the masses. After all, exploitation isn't always a one way street.
As The Big Bang Theory progressed, its focus widened along with the breadth of "nerd culture" permeating the masses. The show attempted to be even more inclusive toward broadening demographics as well. Once actresses Melissa Rauch and Mayim Bialik joined the cast as Bernadette and Amy, respectively, much of the boys' club vibe of the show diminished (but never fully vanished). Strong female characters had their own story arcs and tried their damndest to escape being only seen as one of the principal male cast member's love interest.
Due to the lack of nuanced subject matter in the show, The Big Bang Theory cast a large net, making a target audience hard to pin down. Its broad strokes are arguably the show's biggest strength in cultivating popularity. Very rarely were there deep cuts that would ostracize broad audiences and make them feel like they weren't in on the joke, which might be why some hardened comedy fans, ardent science fiction and fantasy lovers, and comic book nerds pushed back against the bill of goods the show was trying to sell them. The Big Bang Theory was speaking a language they all understood, but the topics of discussion were superficial.
Fans of properties that were once maligned by broader audiences have a tendency to put the things they love up on pedestals. When they make connections to characters and stories which make them feel included to some degree, they become precious. They're important in a way so few pop culture experiences are, so when a show that casually references these properties as punchlines or degrading screeds against fans who love them, it can feel like an insult. It feels pandering, and lazy. It's perceived ostracization, even if it isn't the show's intention.
The success of The Big Bang Theory can't really be attributed to fans of the things Sheldon, Leonard and Penny discuss on the show. Sure, at first, this might have helped establish its roots, but it's not enough to account for it's overwhelming popularity or longevity. It also cannot account solely for the vehement hatred many other people hold for the show. A massive point of contention, for example, is what you would call The Big Bang Theory's style of comedy (or lack thereof). We've all seen videos of comedic exchanges on the show played without the laugh track and how awkward it is. It seems as though audience enjoyment is a Pavlovian Effect brought on by hearing laughter rather than actually being entertained. For many, the jokes are groan-inducing, but for comedians and writers who have dedicated their career to the craft of writing jokes, it can be downright painful.
As The Big Bang Theory rides its final, nerdy wave, it's legacy will be one mired in debate. The fact it had so many fans will never be called into question; the proof is in the pudding, as they say. But whether or not history will be kind to the show in the long run (or if those "Bazinga!" t-shirts you bought at FYE will continue to be fashionable) remains to be seen. But odds are, the show's superficiality will eventually become a footnote in comedy and pop culture history... until they reboot it in fifteen years or so, that is.