Too high a bounty allocation makes trustless due to potential fraud. Allocation is important as a consideration in choosing a bounty, and you should choose bounty with a fair allocation of prizes.
It is actually only a matter of perception really. When things are too low, people say, what is the point of working for so little,,, when it is too high they say instead, this company is overestimating a lot of things, I do not trust them.
What is fair is subjective as long as the bounty is in tokens.