Interesting analogy. Psychologically speaking, there's something impressive and tantalizing about not knowing a person's maximum capability. A self-imposed handicap is one way of obscuring one's ceiling.
As for DeSean Jackson, those gaffes are funny, but his and Bolt's celebrations aren't quite comparable. MOST of the time, pre-TD celebrations (dangling the football at the defender, Deion Sanders-style high stepping) doesn't affect the end result: six points. So it's an appearance of handicap without true disadvantage. There's no obscuring of the player's ceiling.
An interesting, semi-mathematical way we might think about it is that the possible results of a celebration-worthy touchdown run are severely quantized (either 0 or 6), while the possible results of a 100m dash are continuous (well, to the hundredth of a second). In essence, you can't REALLY peacock (self-handicap) on a TD celebration run WITHOUT getting eaten.
Adding to the peacock analogy - Bolt helped NBC to it's highest ratings ever. Peacock helping peacock.
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