The job of a lawyer is very important, his success or failure can have a huge impact on his clients. This is why it is necessary to make sure that you have the best possible lawyer to represent you. This is particularly true in cases where there is a lot at stake. In many, but by no means all cases a talented lawyer can overcome a weak case.
The reason that you need a talented lawyer should be obvious; it will give you the best chance of winning. In a perfect world the person who has the best case would win in a court room but this is rarely what happens, far more likely is that the quality of your lawyer will be the deciding factor in whether you win or lose. This is not always the case of course but it is often enough that you want to make sure that you have the best lawyer possible.
It is of course not always necessary to have a talented lawyer; most lawyers actually handle rather mundane work of drawing up and reviewing documents. For most people as long as you have a competent lawyer you will be just fine. However if you are drawing up a contract that is worth hundreds of millions of dollars or if you have to go to court to handle a major case things will be very different. In these cases having the best possible lawyer is critical. This is largely because the more that is at the stake the better the other guy's lawyer is going to be. This means that you have to have a lawyer to match.
One thing to keep in mind is that having a talented lawyer does not mean that you should expect miracles. This happens a lot; people hire a top lawyer and expect that he will win their case no matter how bad it is. Things just don't work this way, if for example you have clearly infringed on a patent even having legendary intellectual property lawyer Mr. Morgan Chu will not ensure that you win your case. This is why it is important to keep your expectations realistic and listen to what your lawyer is telling you.
Obviously it is important to have a talented lawyer, which raises the question of why everybody doesn't have one? The answer of course is that there are a limited number of them which means that the very best lawyers can charge top prices. If you have a lot of money this will of course not be an issue. If on the other hand you are not rich you will need to decide when a talented lawyer is necessary and when you can get away with a merely competent one. This will largely depend on the consequences of the case.