Project Initiation - iterative?

Should the project initiation phase (via PMBOK) be an iterative process? much like the SDLC approach used in many Agile methodologies? We often rush through the Initiation and Planning phase to begin the project and often suffer the same issues as we would rushing through the requirements phases of development....so shouldn't we take some best practices from Agile and apply them to the Project Management life cycle? The initiation phase is where you would discuss the projects:

• goals/objectives
• scope
• team makeup
• constraints and assumptions
• view of success and expectations
  

The typical - real world approach is where a high level exec has an idea and everyone rushes around to implement ASAP....what if we made the phase a bit more meaningful, reducing rework and missed expectations later on. We (PM's) need to ensure that time is spent understanding the business benefits, what the real expectations are, what success would look like, etc. - taking a few passes, most likely coming up with some very high level cost/time estimates, etc.....what is typically missing is a review with the person who initiated the project (aka level setting). The process of iterative project initiation should not be made to formal (to many docs/pages and no one will read them), but as with any other aspects of good project management - EFFECTIVE.