I'm in agreement with you in a lot of ways. I think it is ignorant how people talk about BPA all the time. There never really is a BPA outside of the top 10. Need, and risk assessment has to be taken into account as you say. Many teams actually discount certain prospects completely. I have first hand account of this from talking to some scouts. The biggest one being goaltenders. There are teams/scouts that don't even rank goalies if they don't fit the size requirement.
There really isn't an exact science in all of this. Its all about risk assessment or projection. Think of any ten player segment of the draft, especially outside of the top 10. Have any 10 people rank those players. Thats scouting in a nutshell. Some will rank them based on potential. Some will rank them based on risk. Some will rank them based on a size/skill combo. Some will rank them based on need. etc, etc, etc..... Fact is you must come to some consensus, but then remain flexible on your board. The Oilers biggest need going into this draft when looking at their prospect pool is at the forward position, and really it is everything about it. They currently don't have a single forward in the minors that I would consider a slam dunk NHLer. If the Oilers happen to draft Chychrun with their first pick, I would drop pretty much every defender off my board at that point, unless one falls drastically. With Paygin, Bear, Jones, Reinhart, Klefbom, Nurse and Chychrun, the Oilers would have a deep defensive prospect pool. They would need to focus on their weak forward group. They also need to find a goaltender. Brossoit will likely graduate next year leaving Laurikainen as the only goalie in the system.