There is no reason to visit, unless you are a tourist
????
Someone who lives or works in/near London isn't allowed to enjoy art/culture/music/gardens/history/food?
I can do pubs/cinema/shows/shopping anywhere.
I mean technically those things are available outside of London, but they aren't the same ones! Tadchester local museum isn't the same as the V&A. Many shows don't tour outside of London, or if they do it isn't for years. Lots of restaurants only have London branches. If international bands/singers only due one UK show it is almost always in London.
That's like saying why would I bother going to a nice restaurant, I can get a burger from McDonalds. Or why bother applying for Oxford, I can get a degree from Nottingham Trent. Why bother seeing an arena tour of a world famous singer with full lights, band and staging when I can see someone singing covers in the local pub? Well, yes you can but it's not the same, is it?
Plus there are lots of things you CAN only do in London. There's no Buckingham palace outside of London. No Greenwich observatory if you're interested in science. No Tower of London. No Kew Gardens. No Sky Garden. No British library or national archives if you need to do specific research. No Abba Voyager. No Gods Own Junkyard. No West End. No underground...you don't have to be a tourist to want to do any of those things, just someone who likes or is studying architecture or biology or history or railways or engineering or who just likes music!
As the saying goes, if you're tired of London then you're tired of life. Most people would find something interesting to do there.
If you don't like it, fine, it's hardly an unusual view, but the reason you've given is bizarre. 'I don't like London because it's too busy/smelly/fast paced/expensive/dangerous' - makes sense. 'I don't like London because there's nothing special there'....doesn't. Although if you're the type of person who gives pubs, shops and cinema as an example of what you like to do, then perhaps it does...