The goal isn't to have multiple answers each containing a piece of the puzzle. It's to have a single, correct, comprehensive answer. Bounty provides a means of encouraging answers to tough problems by offering a reward: allowing you to subdivide this reward creates a situation where you're misleading those participating (who think they're competing for a big prize but only receive a portion of it) and potentially discouraging users from taking the time to write a complete answer. 

In short, i think it's a terrible idea. Good, useful answers *will* be rewarded, by the voters who find them good and useful. If you aren't comfortable with the "winner takes all" bounty system, then *just don't use it* - there's no requirement that you do so ever.

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###See also:
[Why Isn’t There a Way to Consolidate Answers?][1]


  [1]: http://meta.stackoverflow.com/questions/7008/why-isnt-there-a-way-to-consolidate-answers