It’s difficult to address this subject without mentioning the relative nature of “perfection” and of “sin”. I’ve always used the following example: If a parent forbids a 2 or 3-year old to go near the top flight of stairs, the parent is dictating for the child what is good and bad. In fact, that is the case for a good period of a child’s development. Rules are set and there is punishment for disobedience. Does that mean that going near the top flight of the stairs is bad? No. The parent does it. It’s only bad for the toddler because the parent says so.
The point is the relativity of the act. I’m sure that someone put a lot of thought into existing arguments about what happened to Adam and Eve and it seems much of it make sense (in a limited way). The fruit was inconsequential. It could have been a rock upon which they were forbidden to sit on. The point was the act of choosing and deciding to determine for themselves what set of rules they would go by. To choose their own would automatically be a rejection of any other. Obedience would no longer be an issue. Maybe the designers of such a story had something, a very fundamental principle to illustrate.
The question of perfection is also relative. What is perfection? I think an instrument such as a piano is perfect. There’s very little room for improvement in it, even after centuries. It fundamentally remains the same. Some other radical change would probably render it NOT a piano but some other new instrument. That means it’s perfect for the reason it was designed. If a being is designed to have the ability to choose using free will, then the possibility for choosing a detrimental course is built in. Otherwise, to prevent certain outcomes would be to pre-program the entity with limitations and less than free will.
The problem I see with all of that is that if there are consequences to choices not sanctioned by God, the serpent or the Devil seems to have received very little by way of results. Yeah, he was cast out of heaven. But it seems he’s OK with that. On top of it, he seems to enjoy wreaking havoc in the world. It also doesn’t make sense why God would allow all of this to happen (especially the suffering), instead of killing Adam & Eve and the Devil and his fallen angels and start over. Nothing God does, as the ultimate arbiter, would be bad or evil or wrong, just as it is not bad or evil or wrong for a parent to forbid a child from approaching the top of the stairs or any other thing that the parent decides in the interest of the child. But that’s the point. The God of A & E is not acting logically…perhaps because he doesn’t exist.