When you practice something, you usually don't practice it in order to impress others who practice the same thing. Unfortunately, this ends up happening in many cases (usually with abstract things such as pure mathematics or classical music, where appreciation is difficult without context). But in most cases, you produce things that can be appreciated by others, regardless of their interest in the process. If you knit your friend or loved one a cool scarf, they don't necessarily need to be interested in knitting to enjoy wearing it. And if you're a great baker, someone doesn't need to know anything about baking to enjoy your creations.
All the same, ordinary people can have valid negative opinions of things that they aren't proficient in. When a scarf has numerous dropped stitches or a pie doesn't taste quite right, many people can make observations and express their distaste. Just because they aren't knitters or bakers doesn't mean that their critique doesn't "count for anything." They might not be able to pinpoint the part of the process where something went wrong, but that still doesn't invalidate their opinion.
In this case, the intended audience of The Phantom Menace was not film makers, it was ordinary people (in contrast to say Birdman, which may be easier to appreciate if you have some insight into the dramatic world). Maybe it was meant to appeal to a younger crowd (I enjoyed it when I first saw it). Maybe it was meant to appeal to fans of the original trilogy. But the fact remains that aaronbrethorst is entitled to his opinion and his opinion is perfectly valid.
P.S. I also don't like The Phantom Menace, but that doesn't really matter.