Yes I agree with you completely, author should be involved because he/ she has visualized the book and is the right person to write the back cover story.

Regarding purpose of writing a book, that may vary from person to person, as it depends on how you define success.

I write not to change people’s thinking but what I have experienced in life.

My book is to share my point of view and I do not care it will sell also or not.

I write because I believe in writing.

Once there is a resolve to continue writing and to learn from previous mistakes I believe such a writer is always successful, irrespective of how many books are actually sold.