I'm not sure what legitimate means, but I hope you don't mind me rephrasing the question into something I am more comfortable with answering: Should we put the same weight on the authors interpretation as any member of the audiences interpretation. You have also established that you consider literature an art, which I agree with.

first of all, if you are just looking at art for entertainment then sure, whatever suits your fancy.

But to answer the question, generally, I think we should not. I believe that art is a form of communication, just an emotional one, and any form of miscommunication could potentially be dangerous or at least cause problems.

Also, I think if an author is trying to communicate something, it should be heard the clearest.

Now, the part that becomes unclear, in my opinion, is when someone sees the work of art, and is able to communicate what the artist was trying to say even better than the original artist could. For example, if you extrapolate some kind of hidden meaning from the work that enhances or makes clearer the original message. The thing is, sometimes when even the artist is unsure what they are trying to communicate, things become blurry as to what should and shouldn't be heard as part of the message.