That sounds perilously close to being a personal attack.
It was a little harsh, but for my part, I'm more inclined to overlook an attack that borders on the personal if the person is a public figure where such attack is directed at the person's public works. If for example, someone where to say, "Celebrim's work on 'The Explicatae Incompositae' proves he just doesn't have the chops to be a great game designer. His work lacks imagination, his technical prowess is limited, and he shows no signs of doing the hard work necessary to finish the project.", I consider that a valid review (even if I disagreed) of my work. In the case where I had actually offered the work up for sale at $39.95 I would expect people to offer up occasionally such scathing reviews of my work. After all, I'd demanded $39.95 from them. The least I could do is suck it up when someone said, "You suck. I feel cheated. Get a new job."
Mearls is hardly my favorite designer either. As I look over
his work, I don't see alot that just jumps out at me as a must have.
My biggest problem with his work on IH is that it doesn't accomplish what I think it was implied it was setting out to accomplish. The IH product wasn't marketed on how well it would play from 1st-5th level, but on how well it would play from 10th level on. What I think most people wanted from the product could be summed up as 'grim-n-gritty low magic and speedy play at high level'. IH never felt like it could deliver.
I think IH is a great game from 1st-5th level. At low levels of play it looks like it could be alot of fun. I very much got the feeling that the product was offered up having never been play tested beyond 3rd or 5th level or so.
I very much got the impression that Mearls found ''grim-n-gritty low magic and speedy play at high level' to be a very hard task to achieve, and that he in effect cheated by taking magical abilities and putting a thin cosmetic of mundaneness on top of them. Painted up high magic play posing as low magic play is just not what I wanted. I can do wuxia just fine with standard D&D.
All that isn't to say that I wouldn't put Mearls on a design team or that I think he should get a different day job. I think Mearls is brilliant at the small scale stuff. I think he's very imaginative, and capable creating very innovative and flavorful subsystems. And he's prolific as anything. If you want words to pad out your work, Mike is definately your man. I just don't think I'd tap Mearls to be head designer for an entire system.