As a general rule, a negotiation precedes an agreement. However, the statement does not hold necessarily in a Cloud environment, although reaching a Service Level Agreement is considered relevant: currently the user submits a request to the provider, that rejects the request only in case the requested service level cannot be met.
In your opinion, a real negotiation, with offers and counter-offers, may positively impact the provisioning of cloud resources? For instance, by proposing alternate solutions that improve resource utilization.