I'm primarily a user of MathOverflow, but sometimes wander here in hope of making an impact. What strikes me, is how differently I'm treated over there and here, which typically means a flurry of down-votes without any explanation, followed by sporadic negative comments. I can understand this even less in case of a feature-request, especially something that might be welcomed by one community and not by another. If a new, optional feature is preferred by, say 10% of the sites, then this way it has no chance of being implemented. Even more so if the users of these sites don't frequent meta.SE. What can I do about this?
The main 'problem' with feature requests on Meta is that downvoting is used to indicate disagreement:
On posts tagged feature-request, voting indicates agreement or disagreement
Just like people aren't required to support/explain their upvote with a comment, they aren't required with downvotes either.
It's perfectly understandable that a Meta Stack Exchange post and Meta MathOverflow post are received so differently. MathOverflow has always been a special site with an audience rarely crossing over to other sites (or maybe just Math.SE). This is absolutely fine, don't get me wrong, but it does mean that opinions which are commonly liked there can be severely opposed on most of the other sites.
(Another example in this regard is the 'Thanks (in advance)' in questions and comments, which seems to be part of the etiquette on MathOverflow, and considered noise on the rest of the network). I'm exaggerating a little, but I hope you get the point.
Combine this with the fact that a lot of people here, including the de-facto head CM, don't like bounties at all, and I can understand why your question has been received so negatively. It's not a badly written question, and you're following the right procedure; it's just that most people here think it's a bad idea.
As noted elsewhere, downvotes on feature requests usually signify disagreement and don't necessarily mean the proposal was badly made.
That said, and speaking generally (I haven't read your other questions), a feature request is expected to make a case. We see a lot of feature requests here on Meta that boil down to "I think it should do this". Yeah, so? Those don't fare well. Instead, explain why the feature request is beneficial. The broader the spectrum of cases you consider, the better. A feature request that is ideal for one site might be neutral or counter-productive on others. A feature request that helps power users might have side effects that hurt new users. A feature request that's tuned for people using full-screen browsers on large 4k devices might be bad for tablet users. And so on.
Finally, voting on Meta is an input to SE, but it's not the only one and probably not the most important one. If you browse the tag here you'll see plenty of very popular feature requests that were never implemented and sometimes outright declined, and you'll find some lower-scoring ones that were implemented because they were critical in some cases or they were easy or they could be done as part of some other work that was already in progress.