A lot of Japanese fans don't like Dai Atlas because he's utterly ruthless in battle, which is perceived as flying against the standard for Autobot leaders as established by Optimus Prime - the argument that his conduct and ethical standard is "unbecoming" for an Autobot leader and perceived as being more ruthlessly Decepticon-like. In TF Zone, Dai Atlas kills every Decepticon that he comes against rather than trying to show them mercy as Optimus Prime would've done; i.e.
+ Devastator = killed with lava
+ King Poseidon & Trypticon = combined with Sonic Bomber and blasted them both to oblivion
+ Predaking = cut in half
...he killed 18 Decepticons in the span of a single episode!![]()
This is just the general consensus of the Japanese fan community, much like how we might say that the Western fan community hates Wheelie or that the Star Wars fandom hates Jar Jar Binks -- obviously not all fans are gonna feel the same way, but that's just generally what the overall perception or feeling toward those character are.
I personally like Dai Atlas. Killing one's opponents in battle during a war may be a cruel but logically justifiable action. And in each instance, he killed them while they were trying to kill him (i.e. he responded to lethality with lethality). It's not like say Optimus Prime in Revenge of the Fallen and Dark of the Moon who killed helpless defeated opponents (i.e. Demolishor and Sentinel Prime); that was more like executing POWs. Impactor was imprisoned on Garrus-9 for executing Decepticon POWs on Pova (re: LSotW). Dai Atlas killed enemy combatants in the middle of combat. And even Optimus Prime's original G1 TFU profile states that his greatest weakness is his compassion and that he would probably be a better military commander if he were more ruthless, but then he simply wouldn't be Optimus Prime!
It's arguably more of a sentimental reason rather than a more objectively reasoned or logical one.But a lot of fans perceive things more sentimentally than logically, like people who hate the live action films because Optimus Prime's a long nose truck w/ chopper flames instead of a plain red and blue cab-over-engine truck (as opposed to disliking the films for say lack of substantial story or logical plotlines
).