Probably a repost, but I find a little ridiculous that a featured question with a bounty of 500 has basically the same visibility (in terms of featured time and positioning in the list) of a question with 50. Can't we have something to improve this ?
I'm not really sure why this needs to be changed. The incentive lies in the number of points that you're offering, not in the guarantee that it will cause yours to be ranked higher in the list of questions.
You're right that people who aren't terribly concerned with acquiring reputation points may not be any more interested in answering your question than any others, but the fact that you've decided to award 500 points instead of 50 should be enough for those who are interested in such things.
I'd prefer that Stack Overflow not start allowing people to "buy" higher rankings or a better sort position for their questions. If you want to see all the questions with bounties, there's a tab for that. The rest of us prefer to see questions centered around our tags of interest, not necessarily the questions that others want us to see really really badly.
I think the type of users who are looking at bountied questions (the featured tab on the homepage, which is sorted by "ending soonest at top") will ABSOLUTELY notice the difference between …
… on the question.