We fear that the broad new enforcement powers provided under SOPA and PIPA could be easily abused against legitimate services like those upon which we depend. These bills would allow entire websites to be blocked without due process, causing collateral damage to the legitimate users of the same services - artists and creators like us who would be censored as a result.
Here is a letter from actual producers of creative works. It’s the companies that benefit from those works that tend to be in favor of SOPA.