This is because it is set over a hundred years ago, a lot has changed in 1 century, fashion, building and roads, these small things make the story how it is.
Because all theses things are so different now, the stories seem almost set in a different world.
The two main reasons that the stories are still popular today is because justice is carried out and Sherlock Holmes is an appealing character with appealing features. For instance he has this bad side (drugs etc), in modern society a bit of a bad boy is considered to be quite cool, as he is a good guy also he is an all round appealing character.
Dr Watson is a medical doctor, He is an intelligent man although Sherlock Holmes intelligence seems superior in any case that needs solving. Dr Watson does not pick up on clues as quickly as Holmes, even though he too is an intelligent man.
Watson is also a caring character, he always makes sure victims are looked after and are ok. For instance he makes sure Helen Stoner is definitely ok at the end of The Speckled Band.
No matter what the situation, Dr Watson is always on the case, this is because he is bored of his medical practice.
He is willing to do as Holmes asks, for instance the long periods of silence. This is because he respects him, and he respects what he needs to do.
He is also very good friends with Holmes, he can have a laugh with him, talk about ‘old times’ confidently.
Besides all this, he looks up to Holmes, he wants to follow in his footsteps in a way, he wants to do as Holmes does. He wants this, even though he knows he is inferior and not as intelligent.
Another way Dr Watson pursues Holmes is when he talks to other people about him. He makes Holmes seem mysterious and great.
The way Sir Arthur Conan Doyle has made Dr Watson speak is also quite interesting. He makes Dr Watson the narrator, this is an interesting thing to do as he is very much part of the story he is telling.
Everything he sees/observes he describes to us with the details we need to know. He always describes everything in the order that they happened.
The other interesting point is that when he is describing a situation sometimes the story will jump to the situation it self, and Dr Watson would be asking a question. This is an interesting way to break up the narrative, and makes the story more interesting.
He also in general uses poetic and elevated language in the way that he converses with Holmes and describes places.
When people use the term ‘side-kick’, it is usually somebody’s assistant, they usually do the jobs the ‘main’ person does not want to do. They are also not as important. Dr Watson is Holmes’ side-kick.
We never realise the whole case or see every clue. This is because we only see/hear what Dr Watson does.
Holmes’ intelligence can be almost sarcastic at points, for instance asking Dr Watson a question which he knows he wont know the answer to, even though he knows the answer him self.
Or if something is mentioned, he will occasionally answer in a foran language, the phrase may not be difficult but it makes him look good.
Although it could also be said he asks Watson questions to open a conversation in which he can explain something or share his findings and theories.
Dr Watson does not approve of such things as drugs, he does not like the fact that Holmes takes drugs such as heroin, but when you look at their relationship it doesn’t seem to matter, also Dr Watson can see so many positive things about Holmes, such as intelligence it seems to make up for his bad habits/addictions.
He also wants women to be treated well and equally. He does all he can to make sure this happens to the women he meets/deals with.
Dr Watson lets the audience see the plastic (wealthy and healthy) Victorian Britain, with the posh people, posh housing and cushy life styles. But he also lets us see the regular life in Britain at the time, this includes poor people, drug addicts and murder. These things are set in the dark alleys, dens and dingy side-streets.
The conditions are not very good, and would have been a real eye-opener to many wealthy people.
All in all Dr Watson is a vital character to the Sherlock Holmes stories, he is the informer of the audience, he knows as much as we do so he is almost part of the audience through out the story. He makes Sherlock Holmes look good due to his inferior intelligence.
He is a fantastic character and has made Sherlock Holmes what he is today!