I'm curious why people set bounties on feature-requests and bugs. AFAIK it won't speed up the implementation or fixing progress of the FR/B, because the coders in SE don't matter about them very much. So why is there bounties? What's the possible intention of the setter?
Yagmoth is correct, it's one way to draw attention to something. However, there are two goals one might be looking to accomplish by doing so:
You also might want to accomplish both. If all you're after is community input, then the bounty is probably your best bet. If what you really want is an official response from us (SO/SE) then it's probably better to just use the contact form instead. This saves you a bit of rep and ensures a paper trail gets created while the right people get pinged.
I can't promise that we'll always be prepared to write an answer to something immediately, but we generally can and will leave a comment to let folks know it hasn't eluded us, and we'll answer as soon as we're able.
In any event, you're welcome to leave a bounty for any reason that you wish - just know that it isn't mandatory in order to make sure we see something that might have fallen through the cracks.
It serve as a poke, to draw attention to it (the bug or feature-request)
It happen as the backlog is really big and some old requests are more than some years old.
As no need to write a question if a duplicate already exist, but if you found a bug today and your duplicate is 3 year old its discouraging, so the bounty allow to draw some attention.