I'm accustomed to holding unpopular opinions. I'm a liberal Democrat living in Arkansas after all. So it doesn't bother me that I'm the only person I know in my little TVD circle of real life friends and Twitter peeps who cared about John Gilbert at all.
Here's the thing: John Gilbert was us. He's a real life character living in a land of fictional beings. He's the reason that parents are always dead or unavailable in YA paranormals.
Obviously, The Vampire Diaries is a fantasy world. There's vampires and werewolves and witches, oh my. It being a fantasy is the only reason Elena and Stefan's relationship is romantic instead of vaguely pedophiliac. Its the reason that Damon can be a romantic leading man and a psychopath, all at the same time.
But John Gilbert isn't a fantasy. He's not a perfect man, and could be an asshole at times. He is, however, a shining example of how a real life parent could behave, were this fantasy world somehow magically transferred to our reality.
A real parent wants their kid nowhere near a vampire, "good" or not. Of course, we all love Stefan and Damon and think that Elena's got two hot vampires to choose from. But if she were my daughter? Not bloody likely. She'd have been on the first plane to boarding school. John might be bigoted towards vampires, but he's not wrong that they bring danger to everyone. Without Stefan's interference, Elena would still have been the doppelganger, but we've no idea what the story would have been like if she'd stayed away from the vampires. Her life might have been better, it might have been worse, and I'm not so sure that a quick death in the Klaus ritual wouldn't have been preferable to all the stress and worry she's had to deal with over the past 2 seasons, at least from John's perspective.
This obviously isn't as simple as I make it sound. John's interference is made more problematic by the fact that he was so absent from Elena's life, so therefore has less right to tell her what to do. There's also the argument that Elena has her own agency and should be able to make her own choices (we'll call this the Stefan Corollary) but just like any other parent, John sees Elena's continued relationships with vampires to be something like drug addiction: its his job as a parent to protect this 17 year old from herself.
In the end, John gave his life to ensure his daughter got to keep her human existence, and I wouldn't be surprised if Elena isn't all the more aware after the great losses suffered in "The Sun Also Rises" that John wasn't entirely crazy in claiming that her involvement with vampires was dangerous for her and everyone she knows. I hope that the writers introduce another character that serves as the same foil John did for all the romantic vampire ideas.
RIP, John Gilbert. You'll be missed, at least by this viewer.