In defense of the film, it was quite innovative. As you mentioned, mostly the way its shot and also the dialogue come to mind in thinking "why is it the best film of all time". But it totally depends on the kind of films you're into, even if it is called "the best film of all time", that is only by those who can in the first place enjoy films that are dated, too talky, stagy, etc. Which Citizen Kane at points certainly is. I wouldn't say even from afar that it is the best film of all time. But I would defend it was the best film of the era under which it was conceived.
Citizen Kane is forward-thinking in ways other film weren't. If you look at Citizen Kane with the 70+ years there's been of cinema evolution since it came out, it looks totally antique. But if you look at any Frank Capra or Howard Hawks movie you'll understand that Orson Welles had a much more mature approach to filmmaking, most of all dialogue overlapping and camera transitions.
And finally another thing that I'd like to defend it's the narrator. Once my mother asked me about Citizen Kane and I told her it was great and she should watch it. She later told me she had tried but couldn't get past the obnoxious narrator voice. But actually when I first saw the film, I thought it was on purpose. Notice how once the narration is over, and the reveal is made that in the first 10 minutes "it was all a cheap documentary all along", the dialogue immediately turns way more natural and witty. So that narrator, being as square as he was, sounds like Orson Welles himself was mocking the over-exaggeration of pronunciation of dialogue in movies itself.
For example, if you see the rest of the films that were nominated for the Academy Awards back in 1942 you'll see that they all pail in comparison to the quality of Citizen Kane. Even The Maltese Falcon, which is a great movie, still works under way simpler camera movements and bigger leaps in credibility. Citizen Kane was more forward-thinking, it's shot with the kind of ambition films would be shot nowadays and the characters are more fleshed-out and flawed.
I'd recommend you to read a little bit about it, it's a very interesting "trivia" film, even if you don't like it. As you pointed out, it inspired countless both famous and infamous films and filmmakers. It might not be the best film I've ever saw, but it does seem to be a big center point of cinema in general, all paths lead to it somehow, given how ahead of its time it was and how many people it inspired. A Wikipedia article would be enough and a second watch wouldn't harm it. If you're really intrigued watch a documentary. "The Battle Over Citizen Kane" seems to be the go-to CK doc.
