Worthwhile to note the people that you're comparing him to. If you took someone with Lesnar's build and put him at 155 pounds, he'd look like a comic book character... and we'd call him Sean Sherk.
Alot of the heavyweights like overeem, Fedor, Frank mir, brock lesnar are all way more bulked than he is and they all did well, well maybe not lesnar.
Why do ppl say hes over muscled. He doesn`t look that big.
There are sort of prototypical builds for each weightclass, or a range of potential builds, and those builds start to seriously impact a fighter's style when there's too much deviation. Palhares is such a case; at middleweight, there aren't a whole lot of guys who can be successful at all when it comes to high level competition while they're build like he is. It just doesn't happen; that's where the criticism comes from.
I really avoid making comparisons about body type to the majority of heavyweight fighters; those guys are just a totally different thing than the other weightclasses.