Why would they do that?

The House ethics committee has announced charges against Charles Rangel. But Rangel could be impeached and thrown out of office and still get reelected in Harlem, so what's the point. I think he's another Alcee Hastings.

One point suggests itself:

[I]n March he surrendered his gavel as Chairman of the tax-writing Ways and Means Committee, not as the result of these accusations or any other pang of conscience, but because a separate investigation concluded that his participation in several corporate-sponsored Caribbean junkets violated House regulations. At the time, his work in raising taxes to pay for ObamaCare was nearly complete.

Maybe he was just too powerful for Nancy Pelosi's liking.