Voldemort's design in the movies was fine

A lot of people often talk about how Voldemort's character and costume design in the films was bad and made Voldemort not scary.

I disagree. I think the main reason Voldemort isn't scary anymore in the later films is that he just gets so much screen time that you get used to his presence. And don't get me wrong, I don't think the filmmakers made a mistake here. It was required by the story, but Voldemort becoming less scary was just the inevitable consequence.

The reason why Voldemort is so scary in the early films is that he is presented as this hidden ancient evil that only manifests in mysterious and very creepy ways (like as a magical face on the back of someones head, or a creepy monster baby). When Voldemort becomes an actual flesh-and-blood character in the story, he will have to start acting in more mundane ways, walking and talking like a regular human, which numbs the creepy factor.

The character design in the movies was fine. If they had opted to make him more monstrous, I think it would have ended up making the character just less believable. All the alternative Voldemort designs by fans I have seen just lopk pretty goofy IMO