You seem to be implicitly claiming that one only earns a right to critique the usability of a given piece of software if one is also capable of debugging and enhancing that software. Do you really believe that?
I don't like the taste of the food because I don't like the cook. Is that what are you defending? Secondly, you have to be an expert or at least knowledgeable to certain extent to talk about ingredients and style of cooking. Throwing 15 ingredients in a heated pan doesn't make you an excellent cook. Just because you can taste something delicious doesn't mean you will know everything about the that food.