Good points.
No finger pointing please , lets just stick to facts and how the business is "run" excuse the pun.
I dont think you get the point to be made that no "running" athlete makes or breaks a brand. No company has to have any athlete. Some may argue Bolts influence on Puma is important , it did give recognition to the brand , but I dont know of a single retailer who would say this is driving sales.
Ego's are a interesting thing in the shoe world and yes they may trump what you would like to be believe what is professional or not.
Conflicts ? Meets have budgets , fair value comes into play , agents all know the meet budget and who is getting what.
"Package deal" is not a correct term as you explain it. Athletes have a perceived market value , shoe companies have a budget , If the agent cannot get what he wants he simply works with another shoe company. There is no barter as you perceive.
A package deal may happen for a meet as an agent will ask to have other athletes come in on the coat tail of the super elite athlete. A director builds a meet around a few elites , they fill the "other" lanes to build a competitive field , they do survey each athlete on how they may balance the specific event.