Criticising without giving alternatives for improvement is just criticising for the sake of it and not exactly constructive
That is just, like, your opinion man.
The utility of criticism is predicated entirely upon what is done with it not upon the manner in which it is delivered. Letting them know something does not work is valuable in and of itself, offering suggestions not necessarily so. These are not students in need of guidance and direction but rather professionals in their chosen career, They know what they are doing, though that does not mean everything will be done well. These writers are as aware as anyone else that effective dialogue has to feel genuine, because whatever work those lines are meant to do, whatever exposition or subtext is meant to be conveyed, it must also carry the perspective, the feelings, and the intentions of a convincing person. Without that human element it is all wasted because the truth is people are mostly interested in other people and art is rarely far removed from the human element. The reason why voice acting is employed is to aide in that pursuit. They already recognize how vital dialogue must be to a game conceived of narrative influences. While the voice you hear and the inflection it offers can breath further life into those words, that does not relieve from those words the burden of their responsibilities. Writers develop a sense for the written word just as musicians acquire an ear for music. Hemingway wrote incredible dialogue with voices so clear one knew who was speaking without reference or confirmation while eschewing anything which was not strictly necessary without losing any of the emotion or vitality behind what was said. Hunter S Thompson used poetry and metaphor circling concepts endlessly before arriving at what he wished to impart, making an adventure of every insight. Different styles, equally satisfying.
No, tell a writer how to write and they will not thank you. They need merely know that their work wants for improvement.