And yet, considering that not all politicians are of noble mind, isn't it possible for one to go into politics with impure intent? Is it not possible that some politicians might see their positions as stepping stones to something more financially lucrative? These politicians could, quite possibly, feather their nests with contacts who owe them favors so that when they leave office they have a more lucrative and successful career as lobbyists--calling in favors they earned while in office?
I would have to agree that a waiting period after a legislator leaves office before being allowed to become a lobbyist is a good idea. I see no real reason to prevent them from ever becoming a lobbyist, some of these retired lawmakers make excellent lobbyists and have the interest of the people they serve in mind.
I assume you're talking about some sort of rule that specifies that legislators can't become lobbyists after they leave office.
If so, I would say that the cost is not outweighed by the benefits. It is a very grave thing to limit a person's freedom to have the job that he or she wants. This is something that a democratic society should do only in the rarest of circumstances. I think that the law that now mandates a one-year waiting period is a good compromise between the desire to avoid corruption and the need to preserve the liberty of the lawmakers.