For instance, Android devices could be cheaper and of better quality if they didnt have to pay Microsoft. Same with drugs, if a pharmacutical doesnt have to pay lawyers, it can put the resources to better use, R&D for instance. Companies are constantly in search in improving their efficiency, meaning adding value for customers and reducing overhead costs, patents are a clearly overhead costs.
The case of the S3 being pulled from the shelves is evidence of preventing competition. That competition should happen in the marketplace, not in the courts.
That it prohibits innovation is clearly demonstrated by the fact that you have to do things different, not neccesairly better. Innovation is taking existing ideas and improving on them, patents prevent that.
That patents do not add value to the end product is obvious, you can't do anything with them. They do present value to the patent holder for all the reasons mentoined above, but add value to the end product, no,..