Because some people just don't want to have their console see in any kind of bad light. Its pretty ridiculous. OP says he loves the controller, says it's comfortable, one of the best he's used but the build quality has been poor. Many posters respond, I love it, it's the best ever, no issues, perhaps it's you.
I wonder if they were on an auto forum, and some guy writes, man this year's model has a faulty transmission or something, had to replace it twice, whether they'd write "oh I think this year's model is perfect, my transmission is fine, maybe you're doing something wrong".
I can't speak for the build quality myself, all I've seen at my friends and from people I talk to, is that there R1 trigger or something sticks sometimes, that and the sticks get really dirty. Will have to see if they also develop this rubber problem.