Since you're a newbie, let me clue you in as to how things work. The majority of the people here ONLY care about seeing sex between the couples. So your arguments are going to fall on deaf ears (or blind eyes since they'll be reading).
Now about your actual arguments. Are we the "sex of supermans"? Personally speaking I'm not. Some here might be and some might not be. But in the end that's irrelavent. We all still have preferences to what we like and what we want to see. You don't have to be a master chef to know that some food is disgusting. You don't need to be some high-end movie critic to know that some movies are horrible. And you don't need to be some "sex superman" to know that some people just suck at having sex. People here aren't looking for porn star sex but they damn sure want to see more than what this couple can do.
Also, they've been here for more than 48 hours, which brings me to my next point. I never understood why people get offended when people criticize a couple. They voluntarily agreed to have their lives open to criticism. OF COURSE PEOPLE ARE GOING TO CRITICIZE THEM, and for whatever reasons they see fit. Now again, personally speaking, I look at the couples for more than just sex, but that doesn't mean I can't acknowledge that their sexual performance is trash. And because, as I stated earlier, that they allowed their home lives to viewed by us, I'm totally within my right to do so. If they can't handle such criticism then they shouldn't have agreed to live in front of the cameras 24/7.