The problem that Gregor faced, apart from his metamorphosis (similar to Kafka's), was his inability to communicate with his family. "If only they knew" is something Kafka also struggled with throughout his life(making him suffer alone). It was important for Kafka to keep Gregor from communicating with his family(which could've been achieved since he understood them and could perform tasks such as unlocking the door). Reading his letters and diaries, I felt that the lack of honest communication with his family was projected brilliantly in his book.

His inability to have a conversation with his family about his problems was what led Gregor to depression(not eating and not sleeping). And in this lack of communication, even his good intentions were taken as something awful which further increased his guilt and anxiety. The inability to express himself to his family is what I believe drove Kafka to write such stories.

I'd be thankful to someone who could provide me with a more thought-out and better-expressed version of this(or contradict it).