It wasn’t a common critique but I’ve known a couple of fans in real life who felt that way. I remember prior to episode I that there were a fair number of older fans that really hated vi and some of them had that or a similar opinion regarding Vader. They also hated the Ewoks about as much as they would come to hate the gungans. At the time personally I thought episode vi was the shit.
Something also to consider is, before 1999, Vader had also been depicted in plenty of third party media, but most thoroughly in
Shadows of the Empire. This whole idea of "humanizing" him was really a matter of knowing he was a flesh and blood person behind the helmet. This wasn't like ANH where you're not even sure if he's even human or TESB where his revelation about his fatherhood could have been a deception.
To draw a comparison, we know Bruce Wayne is a flesh and blood human being like we are but we are also fully aware that he defies the conventions of regular human beings because he is also The Batman. Part of how that works is there is very little media (shows like
Gotham being an exception) that explores who Bruce Wayne was before his parents were murdered. In this manner, we know that, even as a child, Bruce Wayne was not a conventional kid.
Ultimately, despite Dark Vader having turned back to the light in RotJ, there was still a sense that Anakin was someone who defied conventions. Like, he wasn't a normal guy and was more than likely a deeply disturbed individual. I mean, he would have to be given he turned to the dark side in the first place, right?
The same year that Episode I was released was also the release of
The Sixth Sense. Haley Joel Osment plays an incredibly disturbed child in that film and he does an amazing job with it. Now, take Jake Lloyd as Anakain Skywalker in his setting:
>He has been a slave for all his life.
>He has grown up amidst a wasteland.
>He doesn't have a father.
>He is incredibly strong with the force.
Anakin's entire attitude doesn't reflect his background. In fact, the whole initial conversation he has with Padme sounds far too casual when the context for it is entirely due his being able to sense the supernatural. Compare this with Cole Sear (Osment) revealing to Malcolm Crow (Bruce Willis) that he sees dead people. That moment strikes a chord, it is haunting and remarks on the supernatural. The same cannot be said for any interactions that Anakin has with anyone else in Episode 1. Anakin is far too casual and easy going. Anakin doesn't act like an emotionally disturbed individual. He doesn't act like the kind of boy who probably would have had to mature far faster than he has given his lack of a father and his status as a slave.
Suffice it to say, Lucas seems to think young Anakin needs to work within a convention, but that's the problem: the Star Wars setting isn't conventional. Growing up as a slave to a single mother out in the desert isn't conventional. Being the Chosen One endowed with incredible powers capable of prescience is not conventional.